/*
 * Zmanim Java API
 * Copyright (C) 2004-2024 Eliyahu Hershfeld
 *
 * This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General
 * Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
 * details.
 * You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA,
 * or connect to: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 */
package com.kosherjava.zmanim;

import java.util.Calendar;
import java.util.Date;
import com.kosherjava.zmanim.util.AstronomicalCalculator;
import com.kosherjava.zmanim.util.GeoLocation;
import com.kosherjava.zmanim.hebrewcalendar.JewishCalendar;

/**
 * <p>This class extends ZmanimCalendar and provides many more <em>zmanim</em> than available in the ZmanimCalendar. The basis
 * for most <em>zmanim</em> in this class are from the <em>sefer</em> <b><a href="https://hebrewbooks.org/9765">Yisroel
 * Vehazmanim</a></b> by <b><a href="https://en.wikipedia.org/wiki/Yisroel_Dovid_Harfenes">Rabbi Yisrael Dovid Harfenes</a></b>.
 * As an example of the number of different <em>zmanim</em> made available by this class, there are methods to return 18
 * different calculations for <em>alos</em> (dawn), 18 for <em>plag hamincha</em> and 29 for <em>tzais</em> available in this
 * API. The real power of this API is the ease in calculating <em>zmanim</em> that are not part of the library. The methods for
 * <em>zmanim</em> calculations not present in this class or it's superclass  {@link ZmanimCalendar} are contained in the
 * {@link AstronomicalCalendar}, the base class of the calendars in our API since they are generic methods for calculating
 * time based on degrees or time before or after {@link #getSunrise() sunrise} and {@link #getSunset() sunset} and are of interest
 * for calculation beyond <em>zmanim</em> calculations. Here are some examples.
 * <p>First create the Calendar for the location you would like to calculate:
 * 
 * <pre style="background: #FEF0C9; display: inline-block;">
 * String locationName = &quot;Lakewood, NJ&quot;;
 * double latitude = 40.0828; // Lakewood, NJ
 * double longitude = -74.222; // Lakewood, NJ
 * double elevation = 20; // optional elevation correction in Meters
 * // the String parameter in getTimeZone() has to be a valid timezone listed in
 * // {@link java.util.TimeZone#getAvailableIDs()}
 * TimeZone timeZone = TimeZone.getTimeZone(&quot;America/New_York&quot;);
 * GeoLocation location = new GeoLocation(locationName, latitude, longitude, elevation, timeZone);
 * ComplexZmanimCalendar czc = new ComplexZmanimCalendar(location);
 * // Optionally set the date or it will default to today's date
 * czc.getCalendar().set(Calendar.MONTH, Calendar.FEBRUARY);
 * czc.getCalendar().set(Calendar.DAY_OF_MONTH, 8);</pre>
 * <p>
 * <b>Note:</b> For locations such as Israel where the beginning and end of daylight savings time can fluctuate from
 * year to year, if your version of Java does not have an <a href=
 * "https://www.oracle.com/java/technologies/tzdata-versions.html">up to date timezone database</a>, create a
 * {@link java.util.SimpleTimeZone} with the known start and end of DST.
 * To get <em>alos</em> calculated as 14&deg; below the horizon (as calculated in the calendars published in Montreal),
 * add {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90) to the 14&deg; offset to get the desired time:
 * <br><br>
 * <pre style="background: #FEF0C9; display: inline-block;">
 *  Date alos14 = czc.getSunriseOffsetByDegrees({@link AstronomicalCalendar#GEOMETRIC_ZENITH} + 14);</pre>
 * <p>
 * To get <em>mincha gedola</em> calculated based on the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern"
 * >Magen Avraham (MGA)</a> using a <em>shaah zmanis</em> based on the day starting
 * 16.1&deg; below the horizon (and ending 16.1&deg; after sunset) the following calculation can be used:
 * 
 * <pre style="background: #FEF0C9; display: inline-block;">
 * Date minchaGedola = czc.getTimeOffset(czc.getAlos16point1Degrees(), czc.getShaahZmanis16Point1Degrees() * 6.5);</pre>
 * <p>
 * or even simpler using the included convenience methods
 * <pre style="background: #FEF0C9; display: inline-block;">
 * Date minchaGedola = czc.getMinchaGedola(czc.getAlos16point1Degrees(), czc.getShaahZmanis16Point1Degrees());</pre>
 * <p>
 * A little more complex example would be calculating <em>zmanim</em> that rely on a <em>shaah zmanis</em> that is
 * not present in this library. While a drop more complex, it is still rather easy. An example would be to calculate
 * the <a href="https://en.wikipedia.org/wiki/Israel_Isserlein">Trumas Hadeshen</a>'s <em>alos</em> to
 * <em>tzais</em> based <em>plag hamincha</em> as calculated in the Machzikei Hadass calendar in Manchester, England.
 * A number of this calendar's <em>zmanim</em> are calculated based on a day starting at <em>alos</em> of 12&deg; before
 * sunrise and ending at <em>tzais</em> of 7.083&deg; after sunset. Be aware that since the <em>alos</em> and <em>tzais</em>
 * do not use identical degree-based offsets, this leads to <em>chatzos</em> being at a time other than the
 * {@link #getSunTransit() solar transit} (solar midday). To calculate this <em>zman</em>, use the following steps. Note
 * that <em>plag hamincha</em> is 10.75 hours after the start of the day, and the following steps are all that it takes.
 * <br>
 * <pre style="background: #FEF0C9; display: inline-block;">
 * Date plag = czc.getPlagHamincha(czc.getSunriseOffsetByDegrees({@link AstronomicalCalendar#GEOMETRIC_ZENITH} + 12),
 *                              czc.getSunsetOffsetByDegrees({@link AstronomicalCalendar#GEOMETRIC_ZENITH} + ZENITH_7_POINT_083));</pre>
 * <p>
 * Something a drop more challenging, but still simple, would be calculating a <em>zman</em> using the same "complex"
 * offset day used in the above-mentioned Manchester calendar, but for a <em>shaos zmaniyos</em> based <em>zman</em> not
 * supported by this library, such as calculating the point that one should be <em>makpid</em>
 * not to eat on <em>erev Shabbos</em> or <em>erev Yom Tov</em>. This is 9 <em>shaos zmaniyos</em> into the day.
 * <ol>
 *      <li>Calculate the <em>shaah zmanis</em> in milliseconds for this day</li>
 *      <li>Add 9 of these <em>shaos zmaniyos</em> to <em>alos</em> starting at 12&deg;</li>
 * </ol>
 * <br>
 * <pre style="background: #FEF0C9; display: inline-block;">
 * long shaahZmanis = czc.getTemporalHour(czc.getSunriseOffsetByDegrees({@link AstronomicalCalendar#GEOMETRIC_ZENITH} + 12),
 *                                              czc.getSunsetOffsetByDegrees({@link AstronomicalCalendar#GEOMETRIC_ZENITH} + ZENITH_7_POINT_083));
 * Date sofZmanAchila = getTimeOffset(czc.getSunriseOffsetByDegrees({@link AstronomicalCalendar#GEOMETRIC_ZENITH} + 12),
 *                                      shaahZmanis * 9);</pre>
 * <p>
 * Calculating this <em>sof zman achila</em> according to the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a>
 * is simplicity itself.
 * <pre style="background: #FEF0C9; display: inline-block;">
 * Date sofZmanAchila = czc.getTimeOffset(czc.getSunrise(), czc.getShaahZmanisGra() * 9);</pre>
 * 
 * <h2>Documentation from the {@link ZmanimCalendar} parent class</h2>
 * {@inheritDoc}
 * 
 * @author &copy; Eliyahu Hershfeld 2004 - 2024
 */
public class ComplexZmanimCalendar extends ZmanimCalendar {

        /**
         * The zenith of 3.7&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> that <em>tzais</em> is the
         * time it takes to walk 3/4 of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement"
         * >mil</a> at 18 minutes a mil, or 13.5 minutes after sunset. The sun is 3.7&deg; below
         * {@link #GEOMETRIC_ZENITH geometric zenith} at this time in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>.
         * 
         * @see #getTzaisGeonim3Point7Degrees()
         */
        protected static final double ZENITH_3_POINT_7 = GEOMETRIC_ZENITH + 3.7;

        /**
         * The zenith of 3.8&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> that <em>tzais</em> is the
         * time it takes to walk 3/4 of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement"
         * >mil</a> at 18 minutes a mil, or 13.5 minutes after sunset. The sun is 3.8&deg; below
         * {@link #GEOMETRIC_ZENITH geometric zenith} at this time in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>.
         * 
         * @see #getTzaisGeonim3Point8Degrees()
         */
        protected static final double ZENITH_3_POINT_8 = GEOMETRIC_ZENITH + 3.8;

        /**
         * The zenith of 5.95&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> (nightfall) according to some opinions. This calculation is based on the position of
         * the sun 24 minutes after sunset in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
         * which calculates to 5.95&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @see #getTzaisGeonim5Point95Degrees()
         */
        protected static final double ZENITH_5_POINT_95 = GEOMETRIC_ZENITH + 5.95;

        /**
         * The zenith of 7.083&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This is often referred to as
         * 7&deg;5' or 7&deg; and 5 minutes. This calculation is used for calculating <em>alos</em> (dawn) and
         * <em>tzais</em> (nightfall) according to some opinions. This calculation is based on observation of 3 medium-sized
         * stars by Dr. Baruch Cohen in his calendar published in 1899 in Strasbourg, France. This calculates to
         * 7.0833333&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}. The <a href="https://hebrewbooks.org/1053">Sh"Ut
         * Melamed Leho'il</a> in Orach Chaim 30 agreed to this <em>zman</em>, as did the Sh"Ut Bnei Tziyon and the Tenuvas Sadeh.
         * It is very close to the time of the <a href="https://hebrewbooks.org/22044">Mekor Chesed</a> of the Sefer chasidim.
         * It is close to the position of the sun 30 minutes after sunset in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, but not
         * Exactly. The actual position of the sun 30 minutes after sunset in Jerusalem at the equilux is 7.205&deg; and
         * 7.199&deg; at the equinox. See Hazmanim Bahalacha vol 2, pages 520-521 for details.
         * @todo Hyperlink the proper sources.
         * 
         * @see #getTzaisGeonim7Point083Degrees()
         * @see #getBainHashmashosRT13Point5MinutesBefore7Point083Degrees()
         */
        protected static final double ZENITH_7_POINT_083 = GEOMETRIC_ZENITH + 7 + (5.0 / 60);

        /**
         * The zenith of 10.2&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun
         * 45 minutes before {@link #getSunrise() sunrise} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> which
         * calculates to 10.2&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @see #getMisheyakir10Point2Degrees()
         */
        protected static final double ZENITH_10_POINT_2 = GEOMETRIC_ZENITH + 10.2;

        /**
         * The zenith of 11&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun
         * 48 minutes before {@link #getSunrise() sunrise} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
         * calculates to 11&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @see #getMisheyakir11Degrees()
         */
        protected static final double ZENITH_11_DEGREES = GEOMETRIC_ZENITH + 11;

        /**
         * The zenith of 11.5&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun
         * 52 minutes before {@link #getSunrise() sunrise} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
         * calculates to 11.5&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @see #getMisheyakir11Point5Degrees()
         */
        protected static final double ZENITH_11_POINT_5 = GEOMETRIC_ZENITH + 11.5;

        /**
         * The zenith of 13.24&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating Rabbeinu Tam's <em>bain hashmashos</em> according to some opinions.
         * NOTE: See comments on {@link #getBainHashmashosRT13Point24Degrees} for additional details about the degrees.
         * 
         * @see #getBainHashmashosRT13Point24Degrees
         * 
         */
        protected static final double ZENITH_13_POINT_24 = GEOMETRIC_ZENITH + 13.24;
        
        /**
         * The zenith of 19&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>alos</em> according to some opinions.
         * 
         * @see #getAlos19Degrees()
         * @see #ZENITH_19_POINT_8
         */
        protected static final double ZENITH_19_DEGREES = GEOMETRIC_ZENITH + 19;

        /**
         * The zenith of 19.8&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>alos</em> (dawn) and <em>tzais</em> (nightfall) according to some opinions. This calculation is
         * based on the position of the sun 90 minutes after sunset in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> which
         * calculates to 19.8&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @see #getTzais19Point8Degrees()
         * @see #getAlos19Point8Degrees()
         * @see #getAlos90()
         * @see #getTzais90()
         * @see #ZENITH_19_DEGREES
         */
        protected static final double ZENITH_19_POINT_8 = GEOMETRIC_ZENITH + 19.8;

        /**
         * The zenith of 26&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>alos</em> (dawn) and <em>tzais</em> (nightfall) according to some opinions. This calculation is
         * based on the position of the sun {@link #getAlos120() 120 minutes} after sunset in Jerusalem o<a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> which
         * calculates to 26&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}. Since the level of darkness when the sun is
         * 26&deg; and at a point when the level of darkness is long past the 18&deg; point where the darkest point is reached,
         * it should only be used <em>lechumra</em> such as delaying the start of nighttime <em>mitzvos</em> or avoiding eating
         * this early on a fast day.
         * 
         * @see #getAlos26Degrees()
         * @see #getTzais26Degrees()
         * @see #getAlos120()
         * @see #getTzais120()
         */
        protected static final double ZENITH_26_DEGREES = GEOMETRIC_ZENITH + 26.0;

        /**
         * The zenith of 4.37&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> (nightfall) according to some opinions. This calculation is based on the position of
         * the sun {@link #getTzaisGeonim4Point37Degrees() 16 7/8 minutes} after sunset (3/4 of a 22.5-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>) in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
         * which calculates to 4.37&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @see #getTzaisGeonim4Point37Degrees()
         */
        protected static final double ZENITH_4_POINT_37 = GEOMETRIC_ZENITH + 4.37;

        /**
         * The zenith of 4.61&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> (nightfall) according to some opinions. This calculation is based on the position of
         * the sun {@link #getTzaisGeonim4Point37Degrees() 18 minutes} after sunset (3/4 of a 24-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>) in
         * Jerusalem <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox
         * / equilux</a>, which calculates to 4.61&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * @todo add documentation links
         * 
         * @see #getTzaisGeonim4Point61Degrees()
         */
        protected static final double ZENITH_4_POINT_61 = GEOMETRIC_ZENITH + 4.61;

        /**
         * The zenith of 4.8&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;).
         * @todo Add more documentation.
         * @see #getTzaisGeonim4Point8Degrees()
         */
        protected static final double ZENITH_4_POINT_8 = GEOMETRIC_ZENITH + 4.8;

        /**
         * The zenith of 3.65&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> (nightfall) according to some opinions. This calculation is based on the position of
         * the sun {@link #getTzaisGeonim3Point65Degrees() 13.5 minutes} after sunset (3/4 of an 18-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>) in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> which
         * calculates to 3.65&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * @deprecated This will be removed in v3.0.0 since calculations show that this time is earlier than 13.5 minutes at
         *              the <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the
         *              equinox / equilux</a> in Jerusalem.
         * 
         * @see #getTzaisGeonim3Point65Degrees()
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        protected static final double ZENITH_3_POINT_65 = GEOMETRIC_ZENITH + 3.65;

        /**
         * The zenith of 3.676&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;).
         * @todo Add more documentation.
         * @deprecated This will be removed in v3.0.0 since calculations show that this time is earlier than 13.5 minutes at
         *              the <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the
         *              equinox / equilux</a> in Jerusalem.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        protected static final double ZENITH_3_POINT_676 = GEOMETRIC_ZENITH + 3.676;

        /**
         * The zenith of 5.88&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;).
         * @todo Add more documentation.
         */
        protected static final double ZENITH_5_POINT_88 = GEOMETRIC_ZENITH + 5.88;

        /**
         * The zenith of 1.583&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>netz amiti</em> (sunrise) and <em>shkiah amiti</em> (sunset) based on the opinion of the
         * <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>.
         *
         * @see #getSunriseBaalHatanya()
         * @see #getSunsetBaalHatanya()
         */
        protected static final double ZENITH_1_POINT_583 = GEOMETRIC_ZENITH + 1.583;

        /**
         * The zenith of 16.9&deg; below geometric zenith (90&deg;). This calculation is used for determining <em>alos</em>
         * (dawn) based on the opinion of the Baal Hatanya. It is based on the calculation that the time between dawn
         * and <em>netz amiti</em> (sunrise) is 72 minutes, the time that is takes to walk 4 mil at 18 minutes
         * a mil (<a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others). The sun's position at 72
         * minutes before {@link #getSunriseBaalHatanya <em>netz amiti</em> (sunrise)} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> is
         * 16.9&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         *
         * @see #getAlosBaalHatanya()
         */
        protected static final double ZENITH_16_POINT_9 = GEOMETRIC_ZENITH + 16.9;

        /**
         * The zenith of 6&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> / nightfall based on the opinion of the Baal Hatanya. This calculation is based on the
         * position of the sun 24 minutes after {@link #getSunset() sunset} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
         * is 6&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         *
         * @see #getTzaisBaalHatanya()
         */
        protected static final double ZENITH_6_DEGREES = GEOMETRIC_ZENITH + 6;

        /**
         * The zenith of 6.45&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> (nightfall) according to some opinions. This is based on the calculations of <a href=
         * "https://en.wikipedia.org/wiki/Yechiel_Michel_Tucazinsky">Rabbi Yechiel Michel Tucazinsky</a> of the position of
         * the sun no later than {@link #getTzaisGeonim6Point45Degrees() 31 minutes} after sunset in Jerusalem, and at the
         * height of the summer solstice, this <em>zman</em> is 28 minutes after <em>shkiah</em>. This computes to 6.45&deg;
         * below {@link #GEOMETRIC_ZENITH geometric zenith}. This calculation is found in the <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=50536&st=&pgnum=51">Birur Halacha Yoreh Deah 262</a> it the commonly
         * used <em>zman</em> in Israel. It should be noted that this differs from the 6.1&deg;/6.2&deg; calculation for
         * Rabbi Tucazinsky's time as calculated by the Hazmanim Bahalacha Vol II chapter 50:7 (page 515).
         * 
         * @see #getTzaisGeonim6Point45Degrees()
         */
        protected static final double ZENITH_6_POINT_45 = GEOMETRIC_ZENITH + 6.45;
        
        /**
         * The zenith of 7.65&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>misheyakir</em> according to some opinions.
         * 
         * @see #getMisheyakir7Point65Degrees()
         */
        protected static final double ZENITH_7_POINT_65 = GEOMETRIC_ZENITH + 7.65;
        
        /**
         * The zenith of 7.67&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> according to some opinions.
         * 
         * @see #getTzaisGeonim7Point67Degrees()
         */
        protected static final double ZENITH_7_POINT_67 = GEOMETRIC_ZENITH + 7.67;
        
        /**
         * The zenith of 9.3&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>tzais</em> (nightfall) according to some opinions.
         * 
         * @see #getTzaisGeonim9Point3Degrees()
         */
        protected static final double ZENITH_9_POINT_3 = GEOMETRIC_ZENITH + 9.3;
        
        /**
         * The zenith of 9.5&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>misheyakir</em> according to some opinions.
         * 
         * @see #getMisheyakir9Point5Degrees()
         */
        protected static final double ZENITH_9_POINT_5 = GEOMETRIC_ZENITH + 9.5;
        
        /**
         * The zenith of 9.75&deg; below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating <em>alos</em> (dawn) and <em>tzais</em> (nightfall) according to some opinions.
         * 
         * @see #getTzaisGeonim9Point75Degrees()
         */
        protected static final double ZENITH_9_POINT_75 = GEOMETRIC_ZENITH + 9.75;
        
        /**
         * The zenith of 2.1&deg; above {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating the start of <em>bain hashmashos</em> (twilight) of 13.5 minutes before sunset converted to degrees
         * according to the Yereim. As is traditional with degrees below the horizon, this is calculated without refraction
         * and from the center of the sun. It would be 0.833&deg; less without this.
         * 
         * @see #getBainHashmashosYereim2Point1Degrees()
         */
        protected static final double ZENITH_MINUS_2_POINT_1 = GEOMETRIC_ZENITH - 2.1;
        
        /**
         * The zenith of 2.8&deg; above {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating the start of <em>bain hashmashos</em> (twilight) of 16.875 minutes before sunset converted to degrees
         * according to the Yereim. As is traditional with degrees below the horizon, this is calculated without refraction
         * and from the center of the sun. It would be 0.833&deg; less without this.
         * 
         * @see #getBainHashmashosYereim2Point8Degrees()
         */
        protected static final double ZENITH_MINUS_2_POINT_8 = GEOMETRIC_ZENITH - 2.8;
        
        /**
         * The zenith of 3.05&deg; above {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for
         * calculating the start of <em>bain hashmashos</em> (twilight) of 18 minutes before sunset converted to degrees
         * according to the Yereim. As is traditional with degrees below the horizon, this is calculated without refraction
         * and from the center of the sun. It would be 0.833&deg; less without this.
         * 
         * @see #getBainHashmashosYereim3Point05Degrees()
         */
        protected static final double ZENITH_MINUS_3_POINT_05 = GEOMETRIC_ZENITH - 3.05;

        /**
         * The offset in minutes (defaults to 40) after sunset used for <em>tzeit</em> based on calculations of
         * <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah.
         * @see #getTzaisAteretTorah()
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         */
        private double ateretTorahSunsetOffset = 40;

        /**
         * A constructor that takes a {@link GeoLocation} as a parameter.
         * 
         * @param location
         *            the location
         * 
         * @see ZmanimCalendar#ZmanimCalendar(GeoLocation)
         */
        public ComplexZmanimCalendar(GeoLocation location) {
                super(location);
        }

        /**
         * Default constructor will set a default {@link GeoLocation#GeoLocation()}, a default
         * {@link AstronomicalCalculator#getDefault() AstronomicalCalculator} and default the calendar to the current date.
         * 
         * @see AstronomicalCalendar#AstronomicalCalendar()
         */
        public ComplexZmanimCalendar() {
                super();
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a 19.8&deg; dip. This calculation
         * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen
         * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is when the sun is 19.8&deg;
         * below the eastern geometric horizon before sunrise. Dusk for this is when the sun is 19.8&deg; below the western
         * geometric horizon after sunset. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a {@link Long#MIN_VALUE}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public long getShaahZmanis19Point8Degrees() {
                return getTemporalHour(getAlos19Point8Degrees(), getTzais19Point8Degrees());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a 18&deg; dip. This calculation divides
         * the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham
         * (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is when the sun is 18&deg; below the
         * eastern geometric horizon before sunrise. Dusk for this is when the sun is 18&deg; below the western geometric
         * horizon after sunset. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a {@link Long#MIN_VALUE}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public long getShaahZmanis18Degrees() {
                return getTemporalHour(getAlos18Degrees(), getTzais18Degrees());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 26&deg;. This calculation
         * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen
         * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is when the sun is
         * {@link #getAlos26Degrees() 26&deg;} below the eastern geometric horizon before sunrise. Dusk for this is when
         * the sun is {@link #getTzais26Degrees() 26&deg;} below the western geometric horizon after sunset. This day is
         * split into 12 equal parts with each part being a <em>shaah zmanis</em>. Since <em>zmanim</em> that use this
         * method are extremely late or early and at a point when the sky is a long time past the 18&deg; point where the
         * darkest point is reached, <em>zmanim</em> that use this should only be used <em>lechumra</em>, such as
         * delaying the start of nighttime <em>mitzvos</em>.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a {@link Long#MIN_VALUE}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis120Minutes()
         */
        public long getShaahZmanis26Degrees() {
                return getTemporalHour(getAlos26Degrees(), getTzais26Degrees());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 16.1&deg;. This calculation
         * divides the day based on the opinion that the day runs from dawn to dusk. Dawn for this calculation is when the
         * sun is 16.1&deg; below the eastern geometric horizon before sunrise and dusk is when the sun is 16.1&deg; below
         * the western geometric horizon after sunset. This day is split into 12 equal parts with each part being a
         * <em>shaah zmanis</em>.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a {@link Long#MIN_VALUE}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getAlos16Point1Degrees()
         * @see #getTzais16Point1Degrees()
         * @see #getSofZmanShmaMGA16Point1Degrees()
         * @see #getSofZmanTfilaMGA16Point1Degrees()
         * @see #getMinchaGedola16Point1Degrees()
         * @see #getMinchaKetana16Point1Degrees()
         * @see #getPlagHamincha16Point1Degrees()
         */

        public long getShaahZmanis16Point1Degrees() {
                return getTemporalHour(getAlos16Point1Degrees(), getTzais16Point1Degrees());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (solar hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a>. This calculation
         * divides the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is
         * 60 minutes before sunrise and dusk is 60 minutes after sunset. This day is split into 12 equal parts with each
         * part being a <em>shaah zmanis</em>. Alternate methods of calculating a <em>shaah zmanis</em> are available in the
         * subclass {@link ComplexZmanimCalendar}.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getAlos60()
         * @see #getTzais60()
         * @see #getPlagHamincha60Minutes()
         */
        public long getShaahZmanis60Minutes() {
                return getTemporalHour(getAlos60(), getTzais60());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (solar hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a>. This calculation divides the day
         * based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is 72 minutes
         * before sunrise and dusk is 72 minutes after sunset. This day is split into 12 equal parts with each part
         * being a <em>shaah zmanis</em>. Alternate methods of calculating a <em>shaah zmanis</em> are available in the
         * subclass {@link ComplexZmanimCalendar}.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public long getShaahZmanis72Minutes() {
                return getShaahZmanisMGA();
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em> being
         * {@link #getAlos72Zmanis() 72} minutes <em>zmaniyos</em> before {@link #getSunrise() sunrise}. This calculation
         * divides the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation
         * is 72 minutes <em>zmaniyos</em> before sunrise and dusk is 72 minutes <em>zmaniyos</em> after sunset. This day
         * is split into 12 equal parts with each part being a <em>shaah zmanis</em>. This is identical to 1/10th of the day
         * from {@link #getSunrise() sunrise} to {@link #getSunset() sunset}.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Zmanis()
         * @see #getTzais72Zmanis()
         */
        public long getShaahZmanis72MinutesZmanis() {
                return getTemporalHour(getAlos72Zmanis(), getTzais72Zmanis());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 90 minutes. This calculation
         * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen
         * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is 90 minutes before sunrise
         * and dusk is 90 minutes after sunset. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public long getShaahZmanis90Minutes() {
                return getTemporalHour(getAlos90(), getTzais90());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em> being
         * {@link #getAlos90Zmanis() 90} minutes <em>zmaniyos</em> before {@link #getSunrise() sunrise}. This calculation divides
         * the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is 90 minutes
         * <em>zmaniyos</em> before sunrise and dusk is 90 minutes <em>zmaniyos</em> after sunset. This day is split into 12 equal
         * parts with each part being a <em>shaah zmanis</em>. This is 1/8th of the day from {@link #getSunrise() sunrise} to
         * {@link #getSunset() sunset}.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getAlos90Zmanis()
         * @see #getTzais90Zmanis()
         */
        public long getShaahZmanis90MinutesZmanis() {
                return getTemporalHour(getAlos90Zmanis(), getTzais90Zmanis());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos96Zmanis() 96} minutes <em>zmaniyos</em> before {@link #getSunrise() sunrise}. This calculation divides the
         * day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is 96 minutes
         * <em>zmaniyos</em> before sunrise and dusk is 96 minutes <em>zmaniyos</em> after sunset. This day is split into 12
         * equal parts with each part being a <em>shaah zmanis</em>. This is identical to 1/7.5th of the day from
         * {@link #getSunrise() sunrise} to {@link #getSunset() sunset}.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getAlos96Zmanis()
         * @see #getTzais96Zmanis()
         */
        public long getShaahZmanis96MinutesZmanis() {
                return getTemporalHour(getAlos96Zmanis(), getTzais96Zmanis());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the
         * <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah calculated with <em>alos</em> being 1/10th
         * of sunrise to sunset day, or {@link #getAlos72Zmanis() 72} minutes <em>zmaniyos</em> of such a day before
         * {@link #getSunrise() sunrise}, and <em>tzais</em> is usually calculated as {@link #getTzaisAteretTorah() 40
         * minutes} (configurable to any offset via {@link #setAteretTorahSunsetOffset(double)}) after {@link #getSunset()
         * sunset}. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>. Note that with this
         * system, <em>chatzos</em> (midday) will not be the point that the sun is {@link #getSunTransit() halfway across
         * the sky}.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Zmanis()
         * @see #getTzaisAteretTorah()
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         */
        public long getShaahZmanisAteretTorah() {
                return getTemporalHour(getAlos72Zmanis(), getTzaisAteretTorah());
        }
        
        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) used by some <em>zmanim</em> according to the opinion of
         * <a href="https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in the
         * <em>luach</em> of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that is based on a day starting 72 minutes before
         * sunrise in degrees {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ending 14 minutes after sunset in
         * degrees {@link #getTzaisGeonim3Point8Degrees() <em>tzais</em> 3.8&deg;}. This day is split into 12 equal parts with
         * each part being a <em>shaah zmanis</em>. Note that with this system, <em>chatzos</em> (midday) will not be the point
         * that the sun is {@link #getSunTransit() halfway across the sky}. These <em>shaos zmaniyos</em> are used for <em>Mincha
         * Ketana</em> and <em>Plag Hamincha</em>. The 14 minutes are based on 3/4 of an 18 minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement" >mil</a>, with half a minute added for
         * Rav Yosi.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getMinchaKetanaAhavatShalom()
         * @see #getPlagAhavatShalom()
         */
        public long getShaahZmanisAlos16Point1ToTzais3Point8() {
                return getTemporalHour(getAlos16Point1Degrees(), getTzaisGeonim3Point8Degrees());
        }
        
        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) used by some <em>zmanim</em> according to the opinion of
         * <a href="https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in the
         * <em>luach</em> of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that is based on a day starting 72 minutes before
         * sunrise in degrees {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ending 13.5 minutes after sunset in
         * degrees {@link #getTzaisGeonim3Point7Degrees() <em>tzais</em> 3.7&deg;}. This day is split into 12 equal parts with
         * each part being a <em>shaah zmanis</em>. Note that with this system, <em>chatzos</em> (midday) will not be the point
         * that the sun is {@link #getSunTransit() halfway across the sky}. These <em>shaos zmaniyos</em> are used for <em>Mincha
         * Gedola</em> calculation.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getMinchaGedolaAhavatShalom()
         */
        public long getShaahZmanisAlos16Point1ToTzais3Point7() {
                return getTemporalHour(getAlos16Point1Degrees(), getTzaisGeonim3Point7Degrees());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 96 minutes. This calculation
         * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen
         * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is 96 minutes before sunrise
         * and dusk is 96 minutes after sunset. This day is split into 12 equal parts with each part being a <em>shaah
         * zmanis</em>.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public long getShaahZmanis96Minutes() {
                return getTemporalHour(getAlos96(), getTzais96());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 120 minutes. This calculation
         * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen
         * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is 120 minutes before sunrise and
         * dusk is 120 minutes after sunset. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>.
         * Since <em>zmanim</em> that use this method are extremely late or early and at a point when the sky is a long time
         * past the 18&deg; point where the darkest point is reached, <em>zmanim</em> that use this should only be used
         * <em>lechumra</em> only, such as delaying the start of nighttime <em>mitzvos</em>.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis26Degrees()
         */
        public long getShaahZmanis120Minutes() {
                return getTemporalHour(getAlos120(), getTzais120());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos120Zmanis() 120} minutes <em>zmaniyos</em> before {@link #getSunrise() sunrise}. This calculation divides
         * the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is
         * 120 minutes <em>zmaniyos</em> before sunrise and dusk is 120 minutes <em>zmaniyos</em> after sunset. This day is
         * split into 12 equal parts with each part being a <em>shaah zmanis</em>. This is identical to 1/6th of the day from
         * {@link #getSunrise() sunrise} to {@link #getSunset() sunset}. Since <em>zmanim</em> that use this method are
         * extremely late or early and at a point when the sky is a long time past the 18&deg; point where the darkest point
         * is reached, <em>zmanim</em> that use this should only be used <em>lechumra</em> such as delaying the start of
         * nighttime <em>mitzvos</em>.
         * 
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
         *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getAlos120Zmanis()
         * @see #getTzais120Zmanis()
         */
        public long getShaahZmanis120MinutesZmanis() {
                return getTemporalHour(getAlos120Zmanis(), getTzais120Zmanis());
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on sunrise
         * being 120 minutes <em>zmaniyos</em> or 1/6th of the day before sunrise. This is calculated as 10.75 hours after
         * {@link #getAlos120Zmanis() dawn}. The formula used is 10.75 * {@link #getShaahZmanis120MinutesZmanis()} after
         * {@link #getAlos120Zmanis() dawn}. Since the <em>zman</em> based on an extremely early <em>alos</em> and a very
         * late <em>tzais</em>, it should only be used <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis120MinutesZmanis()
         * @see #getAlos120()
         * @see #getTzais120()
         * @see #getPlagHamincha26Degrees()
         * @see #getPlagHamincha120Minutes()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha120MinutesZmanis() {
                return getPlagHamincha(getAlos120Zmanis(), getTzais120Zmanis(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> according to the
         * Magen Avraham with the day starting 120 minutes before sunrise and ending 120 minutes after sunset. This is
         * calculated as 10.75 hours after {@link #getAlos120() dawn 120 minutes}. The formula used is 10.75 {@link
         * #getShaahZmanis120Minutes()} after {@link #getAlos120()}. Since the <em>zman</em> based on an extremely early
         * <em>alos</em> and a very late <em>tzais</em>, it should only be used <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis120Minutes()
         * @see #getPlagHamincha26Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha120Minutes() {
                return getPlagHamincha(getAlos120(), getTzais120(), true);
        }

        /**
         *       * Method to return <em>alos</em> (dawn) calculated as 60 minutes before {@link #getSunrise() sunrise} or
         * {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link #isUseElevation()} setting). This is the
         * time to walk the distance of 4 <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement"
         * >mil</a> at 15 minutes a mil. This seems to be the opinion of the
         * <a href="https://en.wikipedia.org/wiki/Yair_Bacharach">Chavas Yair</a> in the Mekor Chaim, Orach Chaim Ch. 90,
         * though  the Mekor Chaim in Ch. 58 and in the <a href="https://hebrewbooks.org/pdfpager.aspx?req=45193&pgnum=214"
         * >Chut Hashani Ch. 97</a> states that a person walks 3 and a 1/3 mil in an hour, or an 18-minute mil.
         * Also see the <a href=
         * "https://he.wikipedia.org/wiki/%D7%9E%D7%9C%D7%9B%D7%99%D7%90%D7%9C_%D7%A6%D7%91%D7%99_%D7%98%D7%A0%D7%A0%D7%91%D7%95%D7%99%D7%9D"
         * >Divrei Malkiel</a> <a href="https://hebrewbooks.org/pdfpager.aspx?req=803&pgnum=33">Vol. 4, Ch. 20, page 34</a>) who
         * mentions the 15 minute mil <em>lechumra</em> by baking matzos. Also see the <a href=
         * "https://en.wikipedia.org/wiki/Joseph_Colon_Trabotto">Maharik</a> <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=1142&pgnum=216">Ch. 173</a> where the questioner quoting the
         * <a href="https://en.wikipedia.org/wiki/Eliezer_ben_Nathan">Ra'avan</a> is of the opinion that the time to walk a
         * mil is 15 minutes (5 mil in a little over an hour). There are many who believe that there is a
         * <em>ta'us sofer</em> (scribe's error) in the Ra'avan, and it should 4 mil in a little over an hour, or an
         * 18-minute mil. Time based offset calculations are based on the opinion of the
         * <em><a href="https://en.wikipedia.org/wiki/Rishonim">Rishonim</a></em> who stated that the time of the <em>neshef</em>
         * (time between dawn and sunrise) does not vary by the time of year or location but purely depends on the time it takes to
         * walk the distance of 4* mil. {@link #getTzaisGeonim9Point75Degrees()} is a related <em>zman</em> that is a
         * degree-based calculation based on 60 minutes.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}.
         *         documentation.
         *
         * @see #getTzais60()
         * @see #getPlagHamincha60Minutes()
         * @see #getShaahZmanis60Minutes()
         */
        public Date getAlos60() {
                return getTimeOffset(getElevationAdjustedSunrise(), -60 * MINUTE_MILLIS);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated using 72 minutes <em>zmaniyos</em> or 1/10th of the day before
         * sunrise. This is based on an 18-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> so the time for 4 mil is
         * 72 minutes which is 1/10th of a day (12 * 60 = 720) based on the day being from {@link #getSeaLevelSunrise() sea
         * level sunrise} to {@link #getSeaLevelSunset() sea level sunset} or {@link #getSunrise() sunrise} to {@link #getSunset()
         * sunset} (depending on the {@link #isUseElevation()} setting). The actual calculation is {@link #getSeaLevelSunrise()} -
         * ({@link #getShaahZmanisGra()} * 1.2). This calculation is used in the calendars published by the <a href=
         * "https://en.wikipedia.org/wiki/Central_Rabbinical_Congress">Hisachdus Harabanim D'Artzos Habris Ve'Canada</a>.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getShaahZmanisGra()
         */
        public Date getAlos72Zmanis() {
                return getZmanisBasedOffset(-1.2);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated using 96 minutes before {@link #getSunrise() sunrise} or
         * {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link #isUseElevation()} setting) that is based
         * on the time to walk the distance of 4 <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> at 24 minutes a mil.
         * Time based offset calculations for <em>alos</em> are based on the opinion of the <em><a href=
         * "https://en.wikipedia.org/wiki/Rishonim">Rishonim</a></em> who stated that the time of the <em>Neshef</em> (time between
         * dawn and sunrise) does not vary by the time of year or location but purely depends on the time it takes to walk the
         * distance of 4 mil.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         */
        public Date getAlos96() {
                return getTimeOffset(getElevationAdjustedSunrise(), -96 * MINUTE_MILLIS);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated using 90 minutes <em>zmaniyos</em> or 1/8th of the day before
         * {@link #getSunrise() sunrise} or {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link
         * #isUseElevation()} setting). This is based on a 22.5-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> so the time for 4
         * mil is 90 minutes which is 1/8th of a day (12 * 60) / 8 = 90. The day is calculated from {@link
         * #getSeaLevelSunrise() sea level sunrise} to {@link #getSeaLevelSunset() sea level sunset} or {@link #getSunrise()
         * sunrise} to {@link #getSunset() sunset} (depending on the {@link #isUseElevation()}. The actual calculation used
         * is {@link #getSunrise()} - ({@link #getShaahZmanisGra()} * 1.5).
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getShaahZmanisGra()
         */
        public Date getAlos90Zmanis() {
                return getZmanisBasedOffset(-1.5);
        }

        /**
         * This method returns <em>alos</em> (dawn) calculated using 96 minutes <em>zmaniyos</em> or 1/7.5th of the day before
         * {@link #getSunrise() sunrise} or {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link
         * #isUseElevation()} setting). This is based on a 24-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> so the time for 4 mil is 96
         * minutes which is 1/7.5th of a day (12 * 60 / 7.5 = 96). The day is calculated from {@link #getSeaLevelSunrise() sea
         * level sunrise} to {@link #getSeaLevelSunset() sea level sunset} or {@link #getSunrise() sunrise} to {@link #getSunset()
         * sunset} (depending on the {@link #isUseElevation()}. The actual calculation used is {@link #getSunrise()} -
         * ({@link #getShaahZmanisGra()} * 1.6).
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getShaahZmanisGra()
         */
        public Date getAlos96Zmanis() {
                return getZmanisBasedOffset(-1.6);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated using 90 minutes before {@link #getSeaLevelSunrise() sea level
         * sunrise} based on the time to walk the distance of 4 <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> at 22.5 minutes a
         * mil. Time-based offset calculations for <em>alos</em> are based on the opinion of the <em><a href=
         * "https://en.wikipedia.org/wiki/Rishonim">Rishonim</a></em> who stated that the time of the <em>Neshef</em>
         * (time between dawn and sunrise) does not vary by the time of year or location but purely depends on the time it
         * takes to walk the distance of 4 mil.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         */
        public Date getAlos90() {
                return getTimeOffset(getElevationAdjustedSunrise(), -90 * MINUTE_MILLIS);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns <em>alos</em> (dawn) calculated using 120 minutes
         * before {@link #getSeaLevelSunrise() sea level sunrise} (no adjustment for elevation is made) based on the time
         * to walk the distance of 5 <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement"
         * >mil</a> (<em>Ula</em>) at 24 minutes a mil. Time based offset calculations for <em>alos</em> are
         * based on the* opinion of the <em><a href="https://en.wikipedia.org/wiki/Rishonim">Rishonim</a>
         * </em> who stated that the time of the <em>neshef</em> (time between dawn and sunrise) does not vary by the time of
         * year or location but purely depends on the time it takes to walk the distance of 5 mil (<em>Ula</em>). Since
         * this time is extremely early, it should only be used <em>lechumra</em>, such as not eating after this time on a fast
         * day, and not as the start time for <em>mitzvos</em> that can only be performed during the day.
         * 
         * @deprecated This method should be used <em>lechumra</em> only (such as stopping to eat at this time on a fast day),
         *         since it returns a very early time, and if used <em>lekula</em> can result in doing <em>mitzvos hayom</em>
         *         too early according to most opinions. There is no current plan to remove this method from the API, and this
         *         deprecation is intended to alert developers of the danger of using it.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * 
         * @see #getTzais120()
         * @see #getAlos26Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getAlos120() {
                return getTimeOffset(getElevationAdjustedSunrise(), -120 * MINUTE_MILLIS);
        }

        /**
         * This method should be used <em>lechumra</em> only and  method returns <em>alos</em> (dawn) calculated using
         * 120 minutes <em>zmaniyos</em> or 1/6th of the day before {@link #getSunrise() sunrise} or {@link
         * #getSeaLevelSunrise() sea level sunrise} (depending on the {@link #isUseElevation()} setting). This is based
         * on a 24-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> so
         * the time for 5 mil is 120 minutes which is 1/6th of a day (12 * 60 / 6 = 120). The day is calculated
         * from {@link #getSeaLevelSunrise() sea level sunrise} to {@link #getSeaLevelSunset() sea level sunset} or
         * {@link #getSunrise() sunrise} to {@link #getSunset() sunset} (depending on the {@link #isUseElevation()}. The
         * actual calculation used is {@link #getSunrise()} - ({@link #getShaahZmanisGra()} * 2). Since this time is
         * extremely early, it should only be used <em>lechumra</em>, such
         * as not eating after this time on a fast day, and not as the start time for <em>mitzvos</em> that can only be
         * performed during the day.
         * 
         * @deprecated This method should be used <em>lechumra</em> only (such as stopping to eat at this time on a fast day),
         *         since it returns a very early time, and if used <em>lekula</em> can result in doing <em>mitzvos hayom</em>
         *         too early according to most opinions. There is no current plan to remove this method from the API, and this
         *         deprecation is intended to alert developers of the danger of using it.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos120()
         * @see #getAlos26Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getAlos120Zmanis() {
                return getZmanisBasedOffset(-2.0);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns <em>alos</em> (dawn) calculated when the sun is {@link
         * #ZENITH_26_DEGREES 26&deg;} below the eastern geometric horizon before sunrise. This calculation is based on the same
         * calculation of {@link #getAlos120() 120 minutes} but uses a degree-based calculation instead of 120 exact minutes. This
         * calculation is based on the position of the sun 120 minutes before sunrise in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
         * calculates to 26&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}. Since this time is extremely early, it should
         * only be used <em>lechumra</em> only, such as not eating after this time on a fast day, and not as the start time for
         * <em>mitzvos</em> that can only be performed during the day.
         * 
         * @deprecated This method should be used <em>lechumra</em> only (such as stopping to eat at this time on a fast day),
         *         since it returns a very early time, and if used <em>lekula</em> can result in doing <em>mitzvos hayom</em>
         *         too early according to most opinions. There is no current plan to remove this  method from the API, and this
         *         deprecation is intended to alert developers of the danger of using it.
         * 
         * @return the <code>Date</code> representing <em>alos</em>. If the calculation can't be computed such as northern
         *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
         *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_26_DEGREES
         * @see #getAlos120()
         * @see #getTzais120()
         * @see #getTzais26Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getAlos26Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_26_DEGREES);
        }

        /**
         * A method to return <em>alos</em> (dawn) calculated when the sun is {@link #ASTRONOMICAL_ZENITH 18&deg;} below the
         * eastern geometric horizon before sunrise.
         * 
         * @return the <code>Date</code> representing <em>alos</em>. If the calculation can't be computed such as northern
         *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
         *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ASTRONOMICAL_ZENITH
         */
        public Date getAlos18Degrees() {
                return getSunriseOffsetByDegrees(ASTRONOMICAL_ZENITH);
        }
        
        /**
         * A method to return <em>alos</em> (dawn) calculated when the sun is {@link #ZENITH_19_DEGREES 19&deg;} below the
         * eastern geometric horizon before sunrise. This is the <a href="https://en.wikipedia.org/wiki/Maimonides"
         * >Rambam</a>'s <em>alos</em> according to Rabbi Moshe Kosower's <a href=
         * "https://www.worldcat.org/oclc/145454098">Maaglei Tzedek</a>, page 88, <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=33464&pgnum=13">Ayeles Hashachar Vol. I, page 12</a>, <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=55960&pgnum=258">Yom Valayla Shel Torah, Ch. 34, p. 222</a> and 
         * Rabbi Yaakov Shakow's <a href="https://www.worldcat.org/oclc/1043573513">Luach Ikvei Hayom</a>.
         * 
         * @return the <code>Date</code> representing <em>alos</em>. If the calculation can't be computed such as northern
         *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
         *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ASTRONOMICAL_ZENITH
         */
        public Date getAlos19Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_19_DEGREES);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated when the sun is {@link #ZENITH_19_POINT_8 19.8&deg;} below the
         * eastern geometric horizon before sunrise. This calculation is based on the same calculation of
         * {@link #getAlos90() 90 minutes} but uses a degree-based calculation instead of 90 exact minutes. This calculation
         * is based on the position of the sun 90 minutes before sunrise in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
         * calculates to 19.8&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @return the <code>Date</code> representing <em>alos</em>. If the calculation can't be computed such as northern
         *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
         *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_19_POINT_8
         * @see #getAlos90()
         */
        public Date getAlos19Point8Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_19_POINT_8);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated when the sun is {@link #ZENITH_16_POINT_1 16.1&deg;} below the
         * eastern geometric horizon before sunrise. This calculation is based on the same calculation of
         * {@link #getAlos72() 72 minutes} but uses a degree-based calculation instead of 72 exact minutes. This calculation
         * is based on the position of the sun 72 minutes before sunrise in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
         * calculates to 16.1&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @return the <code>Date</code> representing <em>alos</em>. If the calculation can't be computed such as northern
         *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
         *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_16_POINT_1
         * @see #getAlos72()
         */
        public Date getAlos16Point1Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_16_POINT_1);
        }

        /**
         * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link #ZENITH_11_DEGREES
         * 11.5&deg;} below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for calculating
         * <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun 52 minutes
         * before {@link #getSunrise() sunrise} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
         * which calculates to 11.5&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * @todo recalculate.
         * 
         * @return the <code>Date</code> of <em>misheyakir</em>. If the calculation can't be computed such as northern and
         *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
         *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_11_POINT_5
         */
        public Date getMisheyakir11Point5Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_11_POINT_5);
        }

        /**
         * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link #ZENITH_11_DEGREES
         * 11&deg;} below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for calculating
         * <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun 48 minutes
         * before {@link #getSunrise() sunrise} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
         * which calculates to 11&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @return If the calculation can't be computed such as northern and southern locations even south of the Arctic
         *         Circle and north of the Antarctic Circle where the sun may not reach low enough below the horizon for
         *         this calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_11_DEGREES
         */
        public Date getMisheyakir11Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_11_DEGREES);
        }

        /**
         * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link #ZENITH_10_POINT_2
         * 10.2&deg;} below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is used for calculating
         * <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun 45 minutes
         * before {@link #getSunrise() sunrise} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox</a> which calculates
         * to 10.2&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * 
         * @return the <code>Date</code> of <em>misheyakir</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
         *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_10_POINT_2
         */
        public Date getMisheyakir10Point2Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_10_POINT_2);
        }
        
        /**
         * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link #ZENITH_7_POINT_65
         * 7.65&deg;} below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). The degrees are based on a 35/36 minute
         * <em>zman</em> <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the
         * equinox / equilux</a>, when the <em>neshef</em> (twilight) is the shortest. This time is based on <a href=
         * "https://en.wikipedia.org/wiki/Moshe_Feinstein">Rabbi Moshe Feinstein</a> who writes in <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=14677&pgnum=7">Ohr Hachaim Vol. 4, Ch. 6</a>)
         * that <em>misheyakir</em> in New York is 35-40 minutes before sunrise, something that is a drop less than 8&deg;.
         * <a href="https://en.wikipedia.org/wiki/Yisroel_Taplin">Rabbi Yisroel Taplin</a> in <a href=
         * "https://www.worldcat.org/oclc/889556744">Zmanei Yisrael</a> (page 117) notes that <a href=
         * "https://en.wikipedia.org/wiki/Yaakov_Kamenetsky">Rabbi Yaakov Kamenetsky</a> stated that it is not less than 36
         * minutes before sunrise (maybe it is 40 minutes). Sefer Yisrael Vehazmanim (p. 7) quotes the Tamar Yifrach
         * in the name of the <a href="https://en.wikipedia.org/wiki/Joel_Teitelbaum">Satmar Rov</a> that one should be stringent
         * not consider <em>misheyakir</em> before 36 minutes. This is also the accepted <a href=
         * "https://en.wikipedia.org/wiki/Minhag">minhag</a> in <a href=
         * "https://en.wikipedia.org/wiki/Lakewood_Township,_New_Jersey">Lakewood</a> that is used in the <a href=
         * "https://en.wikipedia.org/wiki/Beth_Medrash_Govoha">Yeshiva</a>. This follows the opinion of <a href=
         * "https://en.wikipedia.org/wiki/Shmuel_Kamenetsky">Rabbi Shmuel Kamenetsky</a> who provided the time of 35/36 minutes,
         * but did not provide a degree-based time. Since this <em>zman</em> depends on the level of light, Rabbi Yaakov Shakow
         * presented this degree-based calculations to Rabbi Shmuel Kamenetsky who agreed to them.
         * 
         * @return the <code>Date</code> of <em>misheyakir</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
         *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #ZENITH_7_POINT_65
         * @see #getMisheyakir9Point5Degrees()
         */
        public Date getMisheyakir7Point65Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_7_POINT_65);
        }
        
        /**
         * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link #ZENITH_9_POINT_5
         * 9.5&deg;} below {@link #GEOMETRIC_ZENITH geometric zenith} (90&deg;). This calculation is based on <a href=
         * "https://en.wikipedia.org/wiki/Dovid_Kronglas">Rabbi Dovid Kronglass's</a> Calculation of 45 minutes in Baltimore
         * as mentioned in <a href="https://hebrewbooks.org/pdfpager.aspx?req=20287&pgnum=29">Divrei Chachamim No. 24</a>
         * brought down by the <a href="https://hebrewbooks.org/pdfpager.aspx?req=50535&pgnum=87">Birur Halacha, Tinyana, Ch.
         * 18</a>. This calculates to 9.5&deg;. Also see <a href="https://en.wikipedia.org/wiki/Jacob_Isaac_Neiman">Rabbi Yaakov
         * Yitzchok Neiman</a> in Kovetz Eitz Chaim Vol. 9, p. 202 that the Vya'an Yosef did not want to rely on times earlier
         * than 45 minutes in New York. This <em>zman</em> is also used in the calendars published by Rabbi Hershel Edelstein.
         * As mentioned in Yisroel Vehazmanim, Rabbi Edelstein who was given the 45 minute <em>zman</em> by Rabbi Bick. The
         * calendars published by the <em><a href="https://en.wikipedia.org/wiki/Mizrahi_Jews">Edot Hamizrach</a></em> communities
         * also use this <em>zman</em>. This also follows the opinion of <a href="https://en.wikipedia.org/wiki/Shmuel_Kamenetsky"
         * >Rabbi Shmuel Kamenetsky</a> who provided the time of 36 and 45 minutes, but did not provide a degree-based time. Since
         * this <em>zman</em> depends on the level of light, Rabbi Yaakov Shakow presented these degree-based times to Rabbi Shmuel
         * Kamenetsky who agreed to them.
         * 
         * @return the <code>Date</code> of <em>misheyakir</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
         *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #ZENITH_9_POINT_5
         * @see #getMisheyakir7Point65Degrees()
         */
        public Date getMisheyakir9Point5Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_9_POINT_5);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos19Point8Degrees() 19.8&deg;} before {@link #getSunrise() sunrise}. This
         * time is 3 {@link #getShaahZmanis19Point8Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link
         * #getAlos19Point8Degrees() dawn} based on the opinion of the MGA that the day is calculated from dawn to nightfall
         * with both being 19.8&deg; below sunrise or sunset. This returns the time of 3 *
         * {@link #getShaahZmanis19Point8Degrees()} after {@link #getAlos19Point8Degrees() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis19Point8Degrees()
         * @see #getAlos19Point8Degrees()
         */
        public Date getSofZmanShmaMGA19Point8Degrees() {
                return getSofZmanShma(getAlos19Point8Degrees(), getTzais19Point8Degrees(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos16Point1Degrees() 16.1&deg;} before {@link #getSunrise() sunrise}. This time
         * is 3 {@link #getShaahZmanis16Point1Degrees() <em>shaos zmaniyos</em>} (solar hours) after
         * {@link #getAlos16Point1Degrees() dawn} based on the opinion of the MGA that the day is calculated from
         * dawn to nightfall with both being 16.1&deg; below sunrise or sunset. This returns the time of
         * 3 * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getAlos16Point1Degrees()
         */
        public Date getSofZmanShmaMGA16Point1Degrees() {
                return getSofZmanShma(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos18Degrees() 18&deg;} before {@link #getSunrise() sunrise}. This time is 3
         * {@link #getShaahZmanis18Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos18Degrees() dawn}
         * based on the opinion of the MGA that the day is calculated from dawn to nightfall with both being 18&deg;
         * below sunrise or sunset. This returns the time of 3 * {@link #getShaahZmanis18Degrees()} after
         * {@link #getAlos18Degrees() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis18Degrees()
         * @see #getAlos18Degrees()
         */
        public Date getSofZmanShmaMGA18Degrees() {
                return getSofZmanShma(getAlos18Degrees(), getTzais18Degrees(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos72() 72} minutes before {@link #getSunrise() sunrise}. This time is 3 {@link
         * #getShaahZmanis72Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos72() dawn} based on the opinion
         * of the MGA that the day is calculated from a {@link #getAlos72() dawn} of 72 minutes before sunrise to
         * {@link #getTzais72() nightfall} of 72 minutes after sunset. This returns the time of 3 * {@link
         * #getShaahZmanis72Minutes()} after {@link #getAlos72() dawn}. This class returns an identical time to {@link
         * #getSofZmanShmaMGA()} and is repeated here for clarity.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         * @see #getShaahZmanis72Minutes()
         * @see #getAlos72()
         * @see #getSofZmanShmaMGA()
         */
        public Date getSofZmanShmaMGA72Minutes() {
                return getSofZmanShmaMGA();
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite <em>Shema</em> in the morning) according
         * to the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos72Zmanis() 72} minutes <em>zmaniyos</em>, or 1/10th of the day before
         * {@link #getSunrise() sunrise}. This time is 3 {@link #getShaahZmanis90MinutesZmanis() <em>shaos zmaniyos</em>}
         * (solar hours) after {@link #getAlos72Zmanis() dawn} based on the opinion of the MGA that the day is calculated
         * from a {@link #getAlos72Zmanis() dawn} of 72 minutes <em>zmaniyos</em>, or 1/10th of the day before
         * {@link #getSeaLevelSunrise() sea level sunrise} to {@link #getTzais72Zmanis() nightfall} of 72 minutes
         * <em>zmaniyos</em> after {@link #getSeaLevelSunset() sea level sunset}. This returns the time of 3 *
         * {@link #getShaahZmanis72MinutesZmanis()} after {@link #getAlos72Zmanis() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72MinutesZmanis()
         * @see #getAlos72Zmanis()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Date getSofZmanShmaMGA72MinutesZmanis() {
                return getSofZmanShma(getAlos72Zmanis(), getTzais72Zmanis(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite <em>Shema</em> in the morning) according
         * to the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos90() 90} minutes before {@link #getSunrise() sunrise}. This time is 3
         * {@link #getShaahZmanis90Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos90() dawn} based on
         * the opinion of the MGA that the day is calculated from a {@link #getAlos90() dawn} of 90 minutes before sunrise to
         * {@link #getTzais90() nightfall} of 90 minutes after sunset. This returns the time of 3 *
         * {@link #getShaahZmanis90Minutes()} after {@link #getAlos90() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90Minutes()
         * @see #getAlos90()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Date getSofZmanShmaMGA90Minutes() {
                return getSofZmanShma(getAlos90(), getTzais90(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos90Zmanis() 90} minutes <em>zmaniyos</em> before {@link #getSunrise()
         * sunrise}. This time is 3 {@link #getShaahZmanis90MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after
         * {@link #getAlos90Zmanis() dawn} based on the opinion of the MGA that the day is calculated from a {@link
         * #getAlos90Zmanis() dawn} of 90 minutes <em>zmaniyos</em> before sunrise to {@link #getTzais90Zmanis() nightfall}
         * of 90 minutes <em>zmaniyos</em> after sunset. This returns the time of 3 * {@link #getShaahZmanis90MinutesZmanis()}
         * after {@link #getAlos90Zmanis() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90MinutesZmanis()
         * @see #getAlos90Zmanis()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Date getSofZmanShmaMGA90MinutesZmanis() {
                return getSofZmanShma(getAlos90Zmanis(), getTzais90Zmanis(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos96() 96} minutes before {@link #getSunrise() sunrise}. This time is 3
         * {@link #getShaahZmanis96Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos96() dawn} based on
         * the opinion of the MGA that the day is calculated from a {@link #getAlos96() dawn} of 96 minutes before
         * sunrise to {@link #getTzais96() nightfall} of 96 minutes after sunset. This returns the time of 3 * {@link
         * #getShaahZmanis96Minutes()} after {@link #getAlos96() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis96Minutes()
         * @see #getAlos96()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Date getSofZmanShmaMGA96Minutes() {
                return getSofZmanShma(getAlos96(), getTzais96(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos90Zmanis() 96} minutes <em>zmaniyos</em> before {@link #getSunrise()
         * sunrise}. This time is 3 {@link #getShaahZmanis96MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after
         * {@link #getAlos96Zmanis() dawn} based on the opinion of the MGA that the day is calculated from a {@link
         * #getAlos96Zmanis() dawn} of 96 minutes <em>zmaniyos</em> before sunrise to {@link #getTzais90Zmanis() nightfall}
         * of 96 minutes <em>zmaniyos</em> after sunset. This returns the time of 3 * {@link #getShaahZmanis96MinutesZmanis()}
         * after {@link #getAlos96Zmanis() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis96MinutesZmanis()
         * @see #getAlos96Zmanis()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Date getSofZmanShmaMGA96MinutesZmanis() {
                return getSofZmanShma(getAlos96Zmanis(), getTzais96Zmanis(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite <em>Shema</em> in the morning) calculated
         * as 3 hours (regular clock hours and not <em>shaos zmaniyos</em>) before {@link ZmanimCalendar#getChatzos()}.
         * Generally known as part of the "Komarno" <em>zmanim</em> after <a href=
         * "https://en.wikipedia.org/wiki/Komarno_(Hasidic_dynasty)#Rabbi_Yitzchak_Eisik_Safrin">Rav Yitzchak Eizik of
         * Komarno</a>, a proponent of this calculation, it actually predates him a lot. It is the opinion of the 
         * <em>Shach</em> in the Nekudas Hakesef (Yoreh Deah 184), <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=21638&st=&pgnum=30">Rav Moshe Lifshitz</a> in his commentary
         * <a href="https://hebrewbooks.org/pdfpager.aspx?req=21638&st=&pgnum=50">Lechem Mishneh on Brachos 1:2</a>. It is
         * next brought down about 100 years later by the <a href="https://en.wikipedia.org/wiki/Jacob_Emden">Yaavetz</a>
         * (in his <em>siddur</em>, <a href="https://hebrewbooks.org/pdfpager.aspx?req=7920&st=&pgnum=6">Mor Uktziah Orach
         * Chaim 1</a>, <a href="https://hebrewbooks.org/pdfpager.aspx?req=22309&st=&pgnum=30">Lechem Shamayim, Brachos 1:2</a>
         * and <a href="https://hebrewbooks.org/pdfpager.aspx?req=1408&st=&pgnum=69">She'elos Yaavetz vol. 1 no. 40</a>),
         * Rav Yitzchak Eizik of Komarno in the Ma'aseh Oreg on Mishnayos Brachos 11:2, Shevus Yaakov, Chasan Sofer and others.
         * See Yisrael Vehazmanim <a href="https://hebrewbooks.org/pdfpager.aspx?req=9765&st=&pgnum=83">vol. 1 7:3, page 55 -
         * 62</a>. A variant of this calculation {@link #getSofZmanShmaFixedLocal()} uses {@link #getFixedLocalChatzos() fixed
         * local <em>chatzos</em>} for calculating this type of <em>zman</em>.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see ZmanimCalendar#getChatzos()
         * @see #getSofZmanShmaFixedLocal()
         * @see #getSofZmanTfila2HoursBeforeChatzos()
         * @see #isUseAstronomicalChatzos()
         */
        public Date getSofZmanShma3HoursBeforeChatzos() {
                return getTimeOffset(getChatzos(), -180 * MINUTE_MILLIS);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos120() 120} minutes or 1/6th of the day before {@link #getSunrise() sunrise}.
         * This time is 3 {@link #getShaahZmanis120Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos120()
         * dawn} based on the opinion of the MGA that the day is calculated from a {@link #getAlos120() dawn} of 120 minutes
         * before sunrise to {@link #getTzais120() nightfall} of 120 minutes after sunset. This returns the time of 3
         * {@link #getShaahZmanis120Minutes()} after {@link #getAlos120() dawn}. This is an extremely early <em>zman</em> that
         * is very much a <em>chumra</em>.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis120Minutes()
         * @see #getAlos120()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Date getSofZmanShmaMGA120Minutes() {
                return getSofZmanShma(getAlos120(), getTzais120(), true);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite <em>Shema</em> in the morning) based
         * on the opinion that the day starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ends at
         * {@link #getSeaLevelSunset() sea level sunset}. This is the opinion of the <a href=
         * "https://hebrewbooks.org/40357">\u05D7\u05D9\u05D3\u05D5\u05E9\u05D9
         * \u05D5\u05DB\u05DC\u05DC\u05D5\u05EA \u05D4\u05E8\u05D6\u05F4\u05D4</a> and the <a href=
         * "https://hebrewbooks.org/14799">\u05DE\u05E0\u05D5\u05E8\u05D4 \u05D4\u05D8\u05D4\u05D5\u05E8\u05D4</a> as
         * mentioned by Yisrael Vehazmanim <a href="https://hebrewbooks.org/pdfpager.aspx?req=9765&pgnum=81">vol 1, sec. 7,
         * ch. 3 no. 16</a>. Three <em>shaos zmaniyos</em> are calculated based on this day and added to {@link
         * #getAlos16Point1Degrees() <em>alos</em>} to reach this time. This time is 3 <em>shaos zmaniyos</em> (solar hours)
         * after {@link #getAlos16Point1Degrees() dawn} based on the opinion that the day is calculated from a {@link
         * #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} to {@link #getSeaLevelSunset() sea level sunset}.
         * <b>Note: </b> Based on this calculation <em>chatzos</em> will not be at midday and {@link
         * #isUseAstronomicalChatzosForOtherZmanim()} will be ignored.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em> based on this day. If the calculation can't
         *         be computed such as northern and southern locations even south of the Arctic Circle and north of the
         *         Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a null
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos16Point1Degrees()
         * @see #getSeaLevelSunset()
         */
        public Date getSofZmanShmaAlos16Point1ToSunset() {
                return getSofZmanShma(getAlos16Point1Degrees(), getElevationAdjustedSunset(), false);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) based on the
         * opinion that the day starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ends at
         * {@link #getTzaisGeonim7Point083Degrees() <em>tzais</em> 7.083&deg;}. 3 <em>shaos zmaniyos</em> are calculated
         * based on this day and added to {@link #getAlos16Point1Degrees() <em>alos</em>} to reach this time. This time is 3
         * <em>shaos zmaniyos</em> (temporal hours) after {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} based on
         * the opinion that the day is calculated from a {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} to
         * {@link #getTzaisGeonim7Point083Degrees() <em>tzais</em> 7.083&deg;}.
         * <b>Note: </b> Based on this calculation <em>chatzos</em> will not be at midday and {@link
         * #isUseAstronomicalChatzosForOtherZmanim()} will be ignored.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em> based on this calculation. If the
         *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
         *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
         *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getAlos16Point1Degrees()
         * @see #getTzaisGeonim7Point083Degrees()
         */
        public Date getSofZmanShmaAlos16Point1ToTzaisGeonim7Point083Degrees() {
                return getSofZmanShma(getAlos16Point1Degrees(), getTzaisGeonim7Point083Degrees(), false);
        }

        /**
         * From the GRA in Kol Eliyahu on Berachos #173 that states that <em>zman krias shema</em> is calculated as half the
         * time from {@link #getSeaLevelSunrise() sea level sunrise} to {@link #getFixedLocalChatzos() fixed local chatzos}.
         * The GRA himself seems to contradict this when he stated that <em>zman krias shema</em> is 1/4 of the day from
         * sunrise to sunset. See <em>Sarah Lamoed</em> #25 in Yisroel Vehazmanim Vol. III page 1016.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em> based on this calculation. If the
         *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where
         *         the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getFixedLocalChatzos()
         * 
         * @deprecated As per a conversation Rabbi Yisroel Twerski had with Rabbi Harfenes, this <em>zman</em> published in
         *         the Yisrael Vehazmanim was based on a misunderstanding and should not be used. This deprecated method
         *         will be removed (likely in v3.0) pending confirmation from Rabbi Harfenes.
         */
        @Deprecated // (since="1.3", forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getSofZmanShmaKolEliyahu() {
                Date chatzos = getFixedLocalChatzos();
                if (chatzos == null || getSunrise() == null) {
                        return null;
                }
                long diff = (chatzos.getTime() - getElevationAdjustedSunrise().getTime()) / 2;
                return getTimeOffset(chatzos, -diff);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos19Point8Degrees() 19.8&deg;} before {@link #getSunrise() sunrise}. This time
         * is 4 {@link #getShaahZmanis19Point8Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link
         * #getAlos19Point8Degrees() dawn} based on the opinion of the MGA that the day is calculated from dawn to
         * nightfall with both being 19.8&deg; below sunrise or sunset. This returns the time of 4 * {@link
         * #getShaahZmanis19Point8Degrees()} after {@link #getAlos19Point8Degrees() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis19Point8Degrees()
         * @see #getAlos19Point8Degrees()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Date getSofZmanTfilaMGA19Point8Degrees() {
                return getSofZmanTfila(getAlos19Point8Degrees(), getTzais19Point8Degrees(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos16Point1Degrees() 16.1&deg;} before {@link #getSunrise() sunrise}. This time
         * is 4 {@link #getShaahZmanis16Point1Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link
         * #getAlos16Point1Degrees() dawn} based on the opinion of the MGA that the day is calculated from dawn to
         * nightfall with both being 16.1&deg; below sunrise or sunset. This returns the time of 4 * {@link
         * #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getAlos16Point1Degrees()
         */
        public Date getSofZmanTfilaMGA16Point1Degrees() {
                return getSofZmanTfila(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos18Degrees() 18&deg;} before {@link #getSunrise() sunrise}. This time is 4
         * {@link #getShaahZmanis18Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos18Degrees() dawn}
         * based on the opinion of the MGA that the day is calculated from dawn to nightfall with both being 18&deg;
         * below sunrise or sunset. This returns the time of 4 * {@link #getShaahZmanis18Degrees()} after
         * {@link #getAlos18Degrees() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis18Degrees()
         * @see #getAlos18Degrees()
         */
        public Date getSofZmanTfilaMGA18Degrees() {
                return getSofZmanTfila(getAlos18Degrees(), getTzais18Degrees(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos72() 72} minutes before {@link #getSunrise() sunrise}. This time is 4
         * {@link #getShaahZmanis72Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos72() dawn} based on
         * the opinion of the MGA that the day is calculated from a {@link #getAlos72() dawn} of 72 minutes before
         * sunrise to {@link #getTzais72() nightfall} of 72 minutes after sunset. This returns the time of 4 *
         * {@link #getShaahZmanis72Minutes()} after {@link #getAlos72() dawn}. This class returns an identical time to
         * {@link #getSofZmanTfilaMGA()} and is repeated here for clarity.
         * 
         * @return the <code>Date</code> of the latest <em>zman tfila</em>. If the calculation can't be computed such as in
         *         the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72Minutes()
         * @see #getAlos72()
         * @see #getSofZmanShmaMGA()
         */
        public Date getSofZmanTfilaMGA72Minutes() {
                return getSofZmanTfilaMGA();
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to the morning prayers) according to the opinion of the
         * <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos72Zmanis() 72} minutes <em>zmaniyos</em> before {@link #getSunrise() sunrise}. This time is 4
         * {@link #getShaahZmanis72MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos72Zmanis() dawn}
         * based on the opinion of the MGA that the day is calculated from a {@link #getAlos72Zmanis() dawn} of 72
         * minutes <em>zmaniyos</em> before sunrise to {@link #getTzais72Zmanis() nightfall} of 72 minutes <em>zmaniyos</em>
         * after sunset. This returns the time of 4 * {@link #getShaahZmanis72MinutesZmanis()} after {@link #getAlos72Zmanis() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72MinutesZmanis()
         * @see #getAlos72Zmanis()
         */
        public Date getSofZmanTfilaMGA72MinutesZmanis() {
                return getSofZmanTfila(getAlos72Zmanis(), getTzais72Zmanis(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos90() 90} minutes before {@link #getSunrise() sunrise}. This time is 4
         * {@link #getShaahZmanis90Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos90() dawn} based on
         * the opinion of the MGA that the day is calculated from a {@link #getAlos90() dawn} of 90 minutes before sunrise to
         * {@link #getTzais90() nightfall} of 90 minutes after sunset. This returns the time of 4 *
         * {@link #getShaahZmanis90Minutes()} after {@link #getAlos90() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman tfila</em>. If the calculation can't be computed such as in
         *         the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90Minutes()
         * @see #getAlos90()
         */
        public Date getSofZmanTfilaMGA90Minutes() {
                return getSofZmanTfila(getAlos90(), getTzais90(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to the morning prayers) according to the opinion of the
         * <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos90Zmanis() 90} minutes <em>zmaniyos</em> before {@link #getSunrise() sunrise}. This time is
         * 4 {@link #getShaahZmanis90MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos90Zmanis()
         * dawn} based on the opinion of the MGA that the day is calculated from a {@link #getAlos90Zmanis() dawn}
         * of 90 minutes <em>zmaniyos</em> before sunrise to {@link #getTzais90Zmanis() nightfall} of 90 minutes
         * <em>zmaniyos</em> after sunset. This returns the time of 4 * {@link #getShaahZmanis90MinutesZmanis()} after
         * {@link #getAlos90Zmanis() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90MinutesZmanis()
         * @see #getAlos90Zmanis()
         */
        public Date getSofZmanTfilaMGA90MinutesZmanis() {
                return getSofZmanTfila(getAlos90Zmanis(), getTzais90Zmanis(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos96() 96} minutes before {@link #getSunrise() sunrise}. This time is 4
         * {@link #getShaahZmanis96Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos96() dawn} based on
         * the opinion of the MGA that the day is calculated from a {@link #getAlos96() dawn} of 96 minutes before
         * sunrise to {@link #getTzais96() nightfall} of 96 minutes after sunset. This returns the time of 4 *
         * {@link #getShaahZmanis96Minutes()} after {@link #getAlos96() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman tfila</em>. If the calculation can't be computed such as in
         *         the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis96Minutes()
         * @see #getAlos96()
         */
        public Date getSofZmanTfilaMGA96Minutes() {
                return getSofZmanTfila(getAlos96(), getTzais96(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to the morning prayers) according to the opinion of the
         * <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos96Zmanis() 96} minutes <em>zmaniyos</em> before {@link #getSunrise() sunrise}. This time is
         * 4 {@link #getShaahZmanis96MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos96Zmanis()
         * dawn} based on the opinion of the MGA that the day is calculated from a {@link #getAlos96Zmanis() dawn}
         * of 96 minutes <em>zmaniyos</em> before sunrise to {@link #getTzais96Zmanis() nightfall} of 96 minutes
         * <em>zmaniyos</em> after sunset. This returns the time of 4 * {@link #getShaahZmanis96MinutesZmanis()} after
         * {@link #getAlos96Zmanis() dawn}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90MinutesZmanis()
         * @see #getAlos90Zmanis()
         */
        public Date getSofZmanTfilaMGA96MinutesZmanis() {
                return getSofZmanTfila(getAlos96Zmanis(), getTzais96Zmanis(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos120() 120} minutes before {@link #getSunrise() sunrise} . This time is 4
         * {@link #getShaahZmanis120Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos120() dawn}
         * based on the opinion of the MGA that the day is calculated from a {@link #getAlos120() dawn} of 120
         * minutes before sunrise to {@link #getTzais120() nightfall} of 120 minutes after sunset. This returns the time of
         * 4 * {@link #getShaahZmanis120Minutes()} after {@link #getAlos120() dawn}. This is an extremely early <em>zman</em>
         * that is very much a <em>chumra</em>.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis120Minutes()
         * @see #getAlos120()
         */
        public Date getSofZmanTfilaMGA120Minutes() {
                return getSofZmanTfila(getAlos120(), getTzais120(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) calculated as 2 hours
         * before {@link ZmanimCalendar#getChatzos()}. This is based on the opinions that calculate
         * <em>sof zman krias shema</em> as {@link #getSofZmanShma3HoursBeforeChatzos()}. This returns the time of 2 hours
         * before {@link ZmanimCalendar#getChatzos()}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
         *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see ZmanimCalendar#getChatzos()
         * @see #getSofZmanShma3HoursBeforeChatzos()
         */
        public Date getSofZmanTfila2HoursBeforeChatzos() {
                return getTimeOffset(getChatzos(), -120 * MINUTE_MILLIS);
        }

        /**
         * This method returns <em>mincha gedola</em> calculated as 30 minutes after {@link #getChatzos() <em>chatzos</em>}
         * and not 1/2 of a {@link #getShaahZmanisGra() <em>shaah zmanis</em>} after {@link #getChatzos() <em>chatzos</em>} as
         * calculated by {@link #getMinchaGedola}. Some use this time to delay the start of <em>mincha</em> in the winter when
         * 1/2 of a {@link #getShaahZmanisGra() <em>shaah zmanis</em>} is less than 30 minutes. See
         * {@link #getMinchaGedolaGreaterThan30()} for a convenience method that returns the later of the 2 calculations. One
         * should not use this time to start <em>mincha</em> before the standard {@link #getMinchaGedola() <em>mincha gedola</em>}.
         * See Shulchan Aruch <a href="https://hebrewbooks.org/pdfpager.aspx?req=49624&st=&pgnum=291">Orach Chayim 234:1</a> and
         * the Shaar Hatziyon <em>seif katan ches</em>. Since this calculation is a fixed 30 minutes of regular clock time after
         * <em>chatzos</em>, even if {@link #isUseAstronomicalChatzosForOtherZmanim()} is <code>false</code>, this <em>mincha
         * gedola</em> time will be affected by {@link #isUseAstronomicalChatzos()} and not by
         * {@link #isUseAstronomicalChatzosForOtherZmanim()}.
         * 
         * @return the <code>Date</code> of 30 minutes after <em>chatzos</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getMinchaGedola()
         * @see #getMinchaGedolaGreaterThan30()
         * @see #getChatzos()
         * @see #isUseAstronomicalChatzos()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Date getMinchaGedola30Minutes() {
                return getTimeOffset(getChatzos(), MINUTE_MILLIS * 30);
        }

        /**
         * This method returns the time of <em>mincha gedola</em> according to the Magen Avraham with the day starting 72
         * minutes before sunrise and ending 72 minutes after sunset. This is the earliest time to pray <em>mincha</em>. For
         * more information on this see the documentation on {@link #getMinchaGedola() <em>mincha gedola</em>}. This is
         * calculated as 6.5 {@link #getTemporalHour() solar hours} after <em>alos</em>. The calculation used is 6.5 *
         * {@link #getShaahZmanis72Minutes()} after {@link #getAlos72() <em>alos</em>}. If {@link
         * #isUseAstronomicalChatzosForOtherZmanim()} is set to <code>true</code>, the calculation will be based on 0.5
         * {@link #getHalfDayBasedShaahZmanis(Date, Date) half-day based <em>sha'ah zmanis</em>} between {@link #getChatzos()}
         * and {@link #getTzais72()} after {@link #getChatzos()}.
         * 
         * @see #getAlos72()
         * @see #getMinchaGedola()
         * @see #getMinchaKetana()
         * @see ZmanimCalendar#getMinchaGedola()
         * @see #getChatzos()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         * @return the <code>Date</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaGedola72Minutes() {
                if (isUseAstronomicalChatzosForOtherZmanim()) {
                        return getHalfDayBasedZman(getChatzos(), getTzais72(), 0.5);
                } else {
                        return getMinchaGedola(getAlos72(), getTzais72(), true);
                }
        }

        /**
         * This method returns the time of <em>mincha gedola</em> according to the Magen Avraham with the day starting and
         * ending 16.1&deg; below the horizon. This is the earliest time to pray <em>mincha</em>. For more information on
         * this see the documentation on {@link #getMinchaGedola() <em>mincha gedola</em>}. This is calculated as 6.5
         * {@link #getTemporalHour() solar hours} after <em>alos</em>. The calculation used is 6.5 *
         * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() <em>alos</em>}. If {@link
         * #isUseAstronomicalChatzosForOtherZmanim()} is set to <code>true</code>, the calculation will be based on 0.5
         * {@link #getHalfDayBasedShaahZmanis(Date, Date) half-day based <em>sha'ah zmanis</em>} between {@link #getChatzos()}
         * and {@link #getAlos16Point1Degrees()} after {@link #getChatzos()}.
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getMinchaGedola()
         * @see #getMinchaKetana()
         * @return the <code>Date</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
         *         the sun  may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaGedola16Point1Degrees() {
                if (isUseAstronomicalChatzosForOtherZmanim()) {
                        return getHalfDayBasedZman(getChatzos(), getTzais16Point1Degrees(), 0.5);
                } else {
                        return getMinchaGedola(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
                }
                
        }
        
        /**
         * This method returns the time of <em>mincha gedola</em> based on the opinion of <a href=
         * "https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in the <em>luach</em>
         * of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that <em>mincha gedola</em> is calculated as half a <em>shaah
         * zmanis</em> after <em>chatzos</em> with <em>shaos zmaniyos</em> calculated based on a day starting 72 minutes before sunrise
         * {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ending 13.5 minutes after sunset {@link
         * #getTzaisGeonim3Point7Degrees() <em>tzais</em> 3.7&deg;}. <em>Mincha gedola</em> is the earliest time to pray <em>mincha</em>.
         * The later of this time or 30 clock minutes after <em>chatzos</em> is returned. See {@link #getMinchaGedolaGreaterThan30()}
         * (though that calculation is based on <em>mincha gedola</em> GRA).
         * For more information about <em>mincha gedola</em> see the documentation on {@link #getMinchaGedola() <em>mincha gedola</em>}.
         * Since calculation of this <em>zman</em> involves <em>chatzos</em> that is offset from the center of the astronomical day,
         * {@link #isUseAstronomicalChatzosForOtherZmanim()} is N/A here.
         * @return the <code>Date</code> of the <em>mincha gedola</em>. If the calculation can't be computed such as northern and
         *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not
         *         reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getAlos16Point1Degrees()
         * @see #getTzaisGeonim3Point7Degrees()
         * @see #getShaahZmanisAlos16Point1ToTzais3Point7()
         * @see #getMinchaGedolaGreaterThan30()
         */
        public Date getMinchaGedolaAhavatShalom() {
                if (getChatzos() == null || getMinchaGedola30Minutes() == null || getShaahZmanisAlos16Point1ToTzais3Point7() == Long.MIN_VALUE) {
                        return null;
                } else {
                        return getMinchaGedola30Minutes().compareTo(getTimeOffset(getChatzos(), getShaahZmanisAlos16Point1ToTzais3Point7() / 2)) > 0 ?
                                        getMinchaGedola30Minutes() : getTimeOffset(getChatzos(), getShaahZmanisAlos16Point1ToTzais3Point7() / 2);
                }
        }

        /**
         * FIXME check for synchronous
         * This is a convenience method that returns the later of {@link #getMinchaGedola()} and
         * {@link #getMinchaGedola30Minutes()}. In the winter when 1/2 of a {@link #getShaahZmanisGra() <em>shaah zmanis</em>} is
         * less than 30 minutes {@link #getMinchaGedola30Minutes()} will be returned, otherwise {@link #getMinchaGedola()}
         * will be returned. Since this calculation can be an offset of <em>chatzos</em> (if 30 clock minutes > 1/2 of a <em>shaah
         * zmanis</em>), even if {@link #isUseAstronomicalChatzosForOtherZmanim()} is <code>false</code>, this <em>mincha</em> time
         * may be affected by {@link #isUseAstronomicalChatzos()}.
         * 
         * @return the <code>Date</code> of the later of {@link #getMinchaGedola()} and {@link #getMinchaGedola30Minutes()}.
         *         If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year
         *         where the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getMinchaGedola()
         * @see #getMinchaGedola30Minutes()
         * @see #isUseAstronomicalChatzos()
         * 
         */
        public Date getMinchaGedolaGreaterThan30() {
                if (getMinchaGedola30Minutes() == null || getMinchaGedola() == null) {
                        return null;
                } else {
                        return getMinchaGedola30Minutes().compareTo(getMinchaGedola()) > 0 ? getMinchaGedola30Minutes()
                                        : getMinchaGedola();
                }
        }

        /**
         * This method returns the time of <em>mincha ketana</em> according to the Magen Avraham with the day starting and
         * ending 16.1&deg; below the horizon. This is the preferred earliest time to pray <em>mincha</em> according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others. For more information on
         * this see the documentation on {@link #getMinchaGedola() <em>mincha gedola</em>}. This is calculated as 9.5
         * {@link #getTemporalHour() solar hours} after <em>alos</em>. The calculation used is 9.5 *
         * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() <em>alos</em>}.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getMinchaGedola()
         * @see #getMinchaKetana()
         * @return the <code>Date</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaKetana16Point1Degrees() {
                return getMinchaKetana(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
        }
        
        /**
         * This method returns the time of <em>mincha ketana</em> based on the opinion of <a href=
         * "https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in the <em>luach</em>
         * of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that <em>mincha ketana</em> is calculated as 2.5 <em>shaos
         * zmaniyos</em> before {@link #getTzaisGeonim3Point8Degrees() <em>tzais</em> 3.8&deg;} with <em>shaos zmaniyos</em>
         * calculated based on a day starting at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ending at
         * <em>tzais</em> 3.8&deg;. <em>Mincha ketana</em> is the preferred earliest time to pray <em>mincha</em> according to
         * the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others. For more information
         * on this see the documentation on {@link #getMinchaKetana() <em>mincha ketana</em>}.
         * 
         * @return the <code>Date</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the
         *         sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanisAlos16Point1ToTzais3Point8()
         * @see #getMinchaGedolaAhavatShalom()
         * @see #getPlagAhavatShalom()
         */
        public Date getMinchaKetanaAhavatShalom() {
                return getTimeOffset(getTzaisGeonim3Point8Degrees(), -getShaahZmanisAlos16Point1ToTzais3Point8() * 2.5);
        }

        /**
         * This method returns the time of <em>mincha ketana</em> according to the Magen Avraham with the day
         * starting 72 minutes before sunrise and ending 72 minutes after sunset. This is the preferred earliest time to pray
         * <em>mincha</em> according to the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a>
         * and others. For more information on this see the documentation on {@link #getMinchaGedola() <em>mincha gedola</em>}.
         * This is calculated as 9.5 {@link #getShaahZmanis72Minutes()} after <em>alos</em>. The calculation used is 9.5 *
         * {@link #getShaahZmanis72Minutes()} after {@link #getAlos72() <em>alos</em>}.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getMinchaGedola()
         * @see #getMinchaKetana()
         * @return the <code>Date</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a<code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaKetana72Minutes() {
                return getMinchaKetana(getAlos72(), getTzais72(), true);
        }

        /**
         * This method returns the time of <em>plag hamincha</em> according to the Magen Avraham with the day starting 60
         * minutes before sunrise and ending 60 minutes after sunset. This is calculated as 10.75 hours after
         * {@link #getAlos60() dawn}. The formula used is 10.75 {@link #getShaahZmanis60Minutes()} after {@link #getAlos60()}.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis60Minutes()
         * @see #getAlos60()
         * @see #getTzais60()
         */
        public Date getPlagHamincha60Minutes() {
                return getPlagHamincha(getAlos60(), getTzais60(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> according to the
         * Magen Avraham with the day starting 72 minutes before sunrise and ending 72 minutes after sunset. This is calculated
         * as 10.75 hours after {@link #getAlos72() dawn}. The formula used is 10.75 {@link #getShaahZmanis72Minutes()} after
         * {@link #getAlos72()}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
         * <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis72Minutes()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha72Minutes() {
                return getPlagHamincha(getAlos72(), getTzais72(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> according to the
         * Magen Avraham with the day starting 90 minutes before sunrise and ending 90 minutes after sunset. This is calculated
         * as 10.75 hours after {@link #getAlos90() dawn}. The formula used is 10.75 {@link #getShaahZmanis90Minutes()} after
         * {@link #getAlos90()}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
         * <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis90Minutes()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha90Minutes() {
                return getPlagHamincha(getAlos90(), getTzais90(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> according to the Magen
         * Avraham with the day starting 96 minutes before sunrise and ending 96 minutes after sunset. This is calculated as 10.75
         * hours after {@link #getAlos96() dawn}. The formula used is 10.75 {@link #getShaahZmanis96Minutes()} after
         * {@link #getAlos96()}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
         * <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis96Minutes()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha96Minutes() {
                return getPlagHamincha(getAlos96(), getTzais96(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em>. This is calculated
         * as 10.75 hours after {@link #getAlos96Zmanis() dawn}. The formula used is 10.75 * {@link
         * #getShaahZmanis96MinutesZmanis()} after {@link #getAlos96Zmanis() dawn}. Since <em>plag</em> by this calculation can
         * occur after sunset, it should only be used <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha96MinutesZmanis() {
                return getPlagHamincha(getAlos96Zmanis(), getTzais96Zmanis(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em>. This is calculated
         * as 10.75 hours after {@link #getAlos90Zmanis() dawn}. The formula used is 10.75 * {@link
         * #getShaahZmanis90MinutesZmanis()} after {@link #getAlos90Zmanis() dawn}. Since <em>plag</em> by this calculation can
         * occur after sunset, it should only be used <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha90MinutesZmanis() {
                return getPlagHamincha(getAlos90Zmanis(), getTzais90Zmanis(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em>. This is calculated as
         * 10.75 hours after {@link #getAlos72Zmanis()}. The formula used is 10.75 * {@link #getShaahZmanis72MinutesZmanis()} after
         * {@link #getAlos72Zmanis() dawn}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
         * <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha72MinutesZmanis() {
                return getPlagHamincha(getAlos72Zmanis(), getTzais72Zmanis(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the
         * opinion that the day starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ends at {@link
         * #getTzais16Point1Degrees() <em>tzais</em> 16.1&deg;}. This is calculated as 10.75 hours <em>zmaniyos</em>
         * after {@link #getAlos16Point1Degrees() dawn}. The formula used is 10.75 * {@link #getShaahZmanis16Point1Degrees()}
         * after {@link #getAlos16Point1Degrees()}. Since <em>plag</em> by this calculation can occur after sunset, it
         * should only be used <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
         *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha16Point1Degrees() {
                return getPlagHamincha(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the
         * opinion that the day starts at {@link #getAlos19Point8Degrees() <em>alos</em> 19.8&deg;} and ends at {@link
         * #getTzais19Point8Degrees() <em>tzais</em> 19.8&deg;}. This is calculated as 10.75 hours <em>zmaniyos</em>
         * after {@link #getAlos19Point8Degrees() dawn}. The formula used is 10.75 * {@link
         * #getShaahZmanis19Point8Degrees()} after {@link #getAlos19Point8Degrees()}. Since <em>plag</em> by this
         * calculation can occur after sunset, it should only be used <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
         *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis19Point8Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha19Point8Degrees() {
                return getPlagHamincha(getAlos19Point8Degrees(), getTzais19Point8Degrees(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the
         * opinion that the day starts at {@link #getAlos26Degrees() <em>alos</em> 26&deg;} and ends at {@link
         * #getTzais26Degrees() <em>tzais</em> 26&deg;}. This is calculated as 10.75 hours <em>zmaniyos</em> after {@link
         * #getAlos26Degrees() dawn}. The formula used is 10.75 * {@link #getShaahZmanis26Degrees()} after {@link
         * #getAlos26Degrees()}. Since the <em>zman</em> based on an extremely early <em>alos</em> and a very late
         * <em>tzais</em>, it should only be used <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
         *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis26Degrees()
         * @see #getPlagHamincha120Minutes()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha26Degrees() {
                return getPlagHamincha(getAlos26Degrees(), getTzais26Degrees(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the
         * opinion that the day starts at {@link #getAlos18Degrees() <em>alos</em> 18&deg;} and ends at {@link
         * #getTzais18Degrees() <em>tzais</em> 18&deg;}. This is calculated as 10.75 hours <em>zmaniyos</em> after {@link
         * #getAlos18Degrees() dawn}. The formula used is 10.75 * {@link #getShaahZmanis18Degrees()} after {@link
         * #getAlos18Degrees()}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
         * <em>lechumra</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
         *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
         *         current plan to remove this method from the API, and this deprecation is intended to alert developers
         *         of the danger of using it.
         * 
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
         *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis18Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagHamincha18Degrees() {
                return getPlagHamincha(getAlos18Degrees(), getTzais18Degrees(), true);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the opinion
         * that the day starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ends at {@link #getSunset() sunset}.
         * 10.75 <em>shaos zmaniyos</em> are calculated based on this day and added to {@link #getAlos16Point1Degrees()
         * <em>alos</em>} to reach this time. This time is 10.75 <em>shaos zmaniyos</em> (temporal hours) after {@link
         * #getAlos16Point1Degrees() dawn} based on the opinion that the day is calculated from a {@link #getAlos16Point1Degrees()
         * dawn} of 16.1 degrees before sunrise to {@link #getSeaLevelSunset() sea level sunset}. This returns the time of 10.75 *
         * the calculated <em>shaah zmanis</em> after {@link #getAlos16Point1Degrees() dawn}. Since <em>plag</em> by this
         * calculation can occur after sunset, it should only be used <em>lechumra</em>.
         * 
         * 
         * @return the <code>Date</code> of the <em>plag</em>. If the calculation can't be computed such as northern and southern
         *         locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not reach
         *         low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getAlos16Point1Degrees()
         * @see #getSeaLevelSunset()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getPlagAlosToSunset() {
                return getPlagHamincha(getAlos16Point1Degrees(), getElevationAdjustedSunset(), false);
        }

        /**
         * This method returns the time of <em>plag hamincha</em> based on the opinion that the day starts at
         * {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and ends at {@link #getTzaisGeonim7Point083Degrees()
         * <em>tzais</em>}. 10.75 <em>shaos zmaniyos</em> are calculated based on this day and added to {@link
         * #getAlos16Point1Degrees() <em>alos</em>} to reach this time. This time is 10.75 <em>shaos zmaniyos</em> (temporal
         * hours) after {@link #getAlos16Point1Degrees() dawn} based on the opinion that the day is calculated from a
         * {@link #getAlos16Point1Degrees() dawn} of 16.1 degrees before sunrise to
         * {@link #getTzaisGeonim7Point083Degrees() <em>tzais</em>} . This returns the time of 10.75 * the calculated
         * <em>shaah zmanis</em> after {@link #getAlos16Point1Degrees() dawn}.
         * 
         * @return the <code>Date</code> of the <em>plag</em>. If the calculation can't be computed such as northern and
         *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not
         *         reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getAlos16Point1Degrees()
         * @see #getTzaisGeonim7Point083Degrees()
         */
        public Date getPlagAlos16Point1ToTzaisGeonim7Point083Degrees() {
                return getPlagHamincha(getAlos16Point1Degrees(), getTzaisGeonim7Point083Degrees(), false);
        }
        
        /**
         * This method returns the time of <em>plag hamincha</em> (the earliest time that Shabbos can be started) based on the
         * opinion of <a href="https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in
         * the <em>luach</em> of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that that <em>plag hamincha</em> is calculated
         * as 1.25 <em>shaos zmaniyos</em> before {@link #getTzaisGeonim3Point8Degrees() <em>tzais</em> 3.8&deg;} with <em>shaos
         * zmaniyos</em> calculated based on a day starting at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;} and
         * ending at <em>tzais</em> 3.8&deg;.
         * 
         * @return the <code>Date</code> of the <em>plag</em>. If the calculation can't be computed such as northern and
         *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not
         *         reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanisAlos16Point1ToTzais3Point8()
         * @see #getMinchaGedolaAhavatShalom()
         * @see #getMinchaKetanaAhavatShalom()
         */
        public Date getPlagAhavatShalom() {
                return getTimeOffset(getTzaisGeonim3Point8Degrees(), -getShaahZmanisAlos16Point1ToTzais3Point8() * 1.25);
        }

        /**
         * Method to return the beginning of <em>bain hashmashos</em> of Rabbeinu Tam calculated when the sun is
         * {@link #ZENITH_13_POINT_24 13.24&deg;} below the western {@link #GEOMETRIC_ZENITH geometric horizon} (90&deg;)
         * after sunset. This calculation is based on the same calculation of {@link #getBainHashmashosRT58Point5Minutes()
         * <em>bain hashmashos</em> Rabbeinu Tam 58.5 minutes} but uses a degree-based calculation instead of 58.5 exact
         * minutes. This calculation is based on the position of the sun 58.5 minutes after sunset in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
         * which calculates to 13.24&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}.
         * NOTE: As per Yisrael Vehazmanim Vol. III page 1028, No. 50, a dip of slightly less than 13&deg; should be used.
         * Calculations show that the proper dip to be 13.2456&deg; (truncated to 13.24 that provides about 1.5 second
         * earlier (<em>lechumra</em>) time) below the horizon at that time. This makes a difference of 1 minute and 10
         * seconds in Jerusalem during the Equinox, and 1 minute 29 seconds during the solstice as compared to the proper
         * 13.24&deg; versus 13&deg;. For NY during the solstice, the difference is 1 minute 56 seconds.
         * @todo recalculate the above based on equilux/equinox calculations.
         * 
         * @return the <code>Date</code> of the sun being 13.24&deg; below {@link #GEOMETRIC_ZENITH geometric zenith}
         *         (90&deg;). If the calculation can't be computed such as northern and southern locations even south of the
         *         Arctic Circle and north of the Antarctic Circle where the sun may not reach low enough below the horizon
         *         for this calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #ZENITH_13_POINT_24
         * @see #getBainHashmashosRT58Point5Minutes()
         */
        public Date getBainHashmashosRT13Point24Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_13_POINT_24);
        }
        

        /**
         * Misspelled method name that should be {@link #getBainHashmashosRT13Point24Degrees()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosRT13Point24Degrees() {
                return getBainHashmashosRT13Point24Degrees();
        }

        /**
         * This method returns the beginning of <em>Bain hashmashos</em> of Rabbeinu Tam calculated as a 58.5
         * minute offset after sunset. <em>bain hashmashos</em> is 3/4 of a <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before <em>tzais</em> or 3 1/4
         * mil after sunset. With a mil calculated as 18 minutes, 3.25 * 18 = 58.5 minutes.
         * 
         * @return the <code>Date</code> of 58.5 minutes after sunset. If the calculation can't be computed such as in the
         *         Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
         *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         */
        public Date getBainHashmashosRT58Point5Minutes() {
                return getTimeOffset(getElevationAdjustedSunset(), 58.5 * MINUTE_MILLIS);
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosRT58Point5Minutes()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosRT58Point5Minutes() {
                return getBainHashmashosRT58Point5Minutes();
        }

        /**
         * This method returns the beginning of <em>bain hashmashos</em> based on the calculation of 13.5 minutes (3/4 of an
         * 18-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>) before
         * <em>shkiah</em> calculated as {@link #getTzaisGeonim7Point083Degrees() 7.083&deg;}.
         * 
         * @return the <code>Date</code> of the <em>bain hashmashos</em> of Rabbeinu Tam in this calculation. If the
         *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
         *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
         *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getTzaisGeonim7Point083Degrees()
         */
        public Date getBainHashmashosRT13Point5MinutesBefore7Point083Degrees() {
                return getTimeOffset(getSunsetOffsetByDegrees(ZENITH_7_POINT_083), -13.5 * MINUTE_MILLIS);
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosRT13Point5MinutesBefore7Point083Degrees()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosRT13Point5MinutesBefore7Point083Degrees() {
                return getBainHashmashosRT13Point5MinutesBefore7Point083Degrees();
        }

        /**
         * This method returns the beginning of <em>bain hashmashos</em> of Rabbeinu Tam calculated according to the
         * opinion of the <em>Divrei Yosef</em> (see Yisrael Vehazmanim) calculated 5/18th (27.77%) of the time between
         * <em>alos</em> (calculated as 19.8&deg; before sunrise) and sunrise. This is added to sunset to arrive at the time
         * for <em>bain hashmashos</em> of Rabbeinu Tam.
         * 
         * @return the <code>Date</code> of <em>bain hashmashos</em> of Rabbeinu Tam for this calculation. If the
         *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
         *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
         *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getBainHashmashosRT2Stars() {
                Date alos19Point8 = getAlos19Point8Degrees();
                Date sunrise = getElevationAdjustedSunrise();
                if (alos19Point8 == null || sunrise == null) {
                        return null;
                }
                return getTimeOffset(getElevationAdjustedSunset(), (sunrise.getTime() - alos19Point8.getTime()) * (5 / 18d));
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosRT2Stars()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosRT2Stars() {
                return getBainHashmashosRT2Stars();
        }
        
        /**
         * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
         * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as 18 minutes
         * or 3/4 of a 24-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement"
         * >mil</a> before sunset. According to the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and
         * <em>tzais</em> or nightfall starts at sunset.
         * 
         * @return the <code>Date</code> of 18 minutes before sunset. If the calculation can't be computed such as in the
         *         Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
         *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getBainHashmashosYereim3Point05Degrees()
         */
        public Date getBainHashmashosYereim18Minutes() {
                return getTimeOffset(getElevationAdjustedSunset(), -18 * MINUTE_MILLIS);
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosYereim18Minutes()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosYereim18Minutes() {
                return getBainHashmashosYereim18Minutes();
        }
        
        /**
         * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
         * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as the sun's
         * position 3.05&deg; above the horizon <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
         * its position 18 minutes or 3/4 of an 24-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before sunset. According to
         * the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and <em>tzais</em> or nightfall starts at
         * sunset. Note that <em>lechumra</em> (of about 14 seconds) a refraction value of 0.5166&deg; as opposed to the
         * traditional 0.566&deg; is used. This is more inline with the actual refraction in <em>Eretz Yisrael</em> and is
         * brought down by <a href=
         * "http://beinenu.com/rabbis/%D7%94%D7%A8%D7%91-%D7%99%D7%93%D7%99%D7%93%D7%99%D7%94-%D7%9E%D7%A0%D7%AA">Rabbi
         * Yedidya Manet</a> in his <a href="https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei Halacha
         * Lema’aseh</a> (p. 11). That is the first source that I am aware of that calculates degree-based Yereim
         * <em>zmanim</em>. The 0.5166&deg; refraction is also used by the <a href="https://zmanim.online/">Luach Itim
         * Lebinah</a>. Calculating the Yereim's <em>bain hashmashos</em> using 18-minute based degrees is also suggested
         * in the upcoming 8th edition of the zmanim Kehilchasam. For more details, see the article <a href=
         * "https://kosherjava.com/2020/12/07/the-yereims-bein-hashmashos/">The Yereim’s <em>Bein Hashmashos</em></a>.
         * 
         * @todo recalculate based on equinox/equilux
         * @return the <code>Date</code> of the sun's position 3.05&deg; minutes before sunset. If the calculation can't
         *         be computed such as in the Arctic Circle where there is at least one day a year where the sun does not
         *         rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on
         *         top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #ZENITH_MINUS_3_POINT_05
         * @see #getBainHashmashosYereim18Minutes()
         * @see #getBainHashmashosYereim2Point8Degrees()
         * @see #getBainHashmashosYereim2Point1Degrees()
         */
        public Date getBainHashmashosYereim3Point05Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_MINUS_3_POINT_05);
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosYereim3Point05Degrees()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosYereim3Point05Degrees() {
                return getBainHashmashosYereim3Point05Degrees();
        }
        
        
        /**
         * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
         * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as 16.875
         * minutes or 3/4 of a 22.5-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before sunset. According
         * to the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and <em>tzais</em> or nightfall starts
         * at sunset.
         * 
         * @return the <code>Date</code> of 16.875 minutes before sunset. If the calculation can't be computed such as in the
         *         Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
         *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getBainHashmashosYereim2Point8Degrees()
         */
        public Date getBainHashmashosYereim16Point875Minutes() {
                return getTimeOffset(getElevationAdjustedSunset(), -16.875 * MINUTE_MILLIS);
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosYereim16Point875Minutes()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosYereim16Point875Minutes() {
                return getBainHashmashosYereim16Point875Minutes();
        }
        
        /**
         * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
         * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as the sun's
         * position 2.8&deg; above the horizon <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
         * its position 16.875 minutes or 3/4 of an 18-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before sunset. According to
         * the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and <em>tzais</em> or nightfall
         * starts at sunset. Details, including how the degrees were calculated can be seen in the documentation of
         * {@link #getBainHashmashosYereim3Point05Degrees()}.
         * 
         * @return the <code>Date</code> of the sun's position 2.8&deg; minutes before sunset. If the calculation can't
         *         be computed such as in the Arctic Circle where there is at least one day a year where the sun does not
         *         rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on
         *         top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #ZENITH_MINUS_2_POINT_8
         * @see #getBainHashmashosYereim16Point875Minutes()
         * @see #getBainHashmashosYereim3Point05Degrees()
         * @see #getBainHashmashosYereim2Point1Degrees()
         */
        public Date getBainHashmashosYereim2Point8Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_MINUS_2_POINT_8);
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosYereim2Point8Degrees()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosYereim2Point8Degrees() {
                return getBainHashmashosYereim2Point8Degrees();
        }
        
        
        /**
         * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
         * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as 13.5 minutes
         * or 3/4 of an 18-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>
         * before sunset. According to the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and
         * <em>tzais</em> or nightfall starts at sunset.
         * 
         * @return the <code>Date</code> of 13.5 minutes before sunset. If the calculation can't be computed such as in the
         *         Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
         *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getBainHashmashosYereim2Point1Degrees()
         */
        public Date getBainHashmashosYereim13Point5Minutes() {
                return getTimeOffset(getElevationAdjustedSunset(), -13.5 * MINUTE_MILLIS);
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosYereim13Point5Minutes()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosYereim13Point5Minutes() {
                return getBainHashmashosYereim13Point5Minutes();
        }
        
        /**
         * This method returns the beginning of <em>bain hashmashos</em> according to the <a href=
         * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as the sun's
         * position 2.1&deg; above the horizon <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> in
         * Yerushalayim, its position 13.5 minutes or 3/4 of an 18-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before sunset. According to the
         * Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and <em>tzais</em> or nightfall starts
         * at sunset. Details, including how the degrees were calculated can be seen in the documentation of
         * {@link #getBainHashmashosYereim3Point05Degrees()}.
         * 
         * @return the <code>Date</code> of the sun's position 2.1&deg; minutes before sunset. If the calculation can't be
         *         computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and
         *         one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #ZENITH_MINUS_2_POINT_1
         * @see #getBainHashmashosYereim13Point5Minutes()
         * @see #getBainHashmashosYereim2Point8Degrees()
         * @see #getBainHashmashosYereim3Point05Degrees()
         */
        public Date getBainHashmashosYereim2Point1Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_MINUS_2_POINT_1);
        }
        
        /**
         * Misspelled method name that should be {@link #getBainHashmashosYereim2Point1Degrees()}.
         * @return the properly spelled version.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getBainHasmashosYereim2Point1Degrees() {
                return getBainHashmashosYereim2Point1Degrees();
        }
        
        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated at the
         * sun's position at {@link #ZENITH_3_POINT_7 3.7&deg;} below the western horizon.
         * 
         * @return the <code>Date</code> representing the time when the sun is 3.7&deg; below sea level.
         * @see #ZENITH_3_POINT_7
         */
        public Date getTzaisGeonim3Point7Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_3_POINT_7);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated at the
         * sun's position at {@link #ZENITH_3_POINT_8 3.8&deg;} below the western horizon.
         * 
         * @return the <code>Date</code> representing the time when the sun is 3.8&deg; below sea level.
         * @see #ZENITH_3_POINT_8
         */
        public Date getTzaisGeonim3Point8Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_3_POINT_8);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated at the
         * sun's position at {@link #ZENITH_5_POINT_95 5.95&deg;} below the western horizon.
         * 
         * @return the <code>Date</code> representing the time when the sun is 5.95&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #ZENITH_5_POINT_95
         */
        public Date getTzaisGeonim5Point95Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_5_POINT_95);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 3/4
         * of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> based on an
         * 18-minute mil, or 13.5 minutes. It is the sun's position at {@link #ZENITH_3_POINT_65 3.65&deg;} below the western
         * horizon. This is a very early <em>zman</em> and should not be relied on without Rabbinical guidance.
         * 
         * @return the <code>Date</code> representing the time when the sun is 3.65&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @deprecated This will be removed in v3.0.0 since calculations show that this time is earlier than 13.5 minutes at
         *              the <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the
         *              equinox / equilux</a> in Jerusalem.
         * @see #ZENITH_3_POINT_65
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getTzaisGeonim3Point65Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_3_POINT_65);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 3/4
         * of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> based on an
         * 18-minute mil, or 13.5 minutes. It is the sun's position at {@link #ZENITH_3_POINT_676 3.676&deg;} below the western
         * horizon based on the calculations of Stanley Fishkind. This is a very early <em>zman</em> and should not be
         * relied on without Rabbinical guidance.
         * 
         * @return the <code>Date</code> representing the time when the sun is 3.676&deg; below sea level. If the
         *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
         *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
         *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @deprecated This will be removed in v3.0.0 since calculations show that this time is earlier than 13.5 minutes at
         *              the <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the
         *              equinox / equilux</a> in Jerusalem.
         * @see #ZENITH_3_POINT_676
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getTzaisGeonim3Point676Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_3_POINT_676);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 3/4
         * of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> based on a
         * 24-minute mil, or 18 minutes. It is the sun's position at {@link #ZENITH_4_POINT_61 4.61&deg;} below the
         * western horizon. This is a very early <em>zman</em> and should not be relied on without Rabbinical guidance.
         * 
         * @return the <code>Date</code> representing the time when the sun is 4.61&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #ZENITH_4_POINT_61
         */
        public Date getTzaisGeonim4Point61Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_4_POINT_61);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 3/4
         * of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>, based on a
         * 22.5-minute mil, or 16 7/8 minutes. It is the sun's position at {@link #ZENITH_4_POINT_37 4.37&deg;} below the western
         * horizon. This is a very early <em>zman</em> and should not be relied on without Rabbinical guidance.
         * 
         * @return the <code>Date</code> representing the time when the sun is 4.37&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #ZENITH_4_POINT_37
         */
        public Date getTzaisGeonim4Point37Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_4_POINT_37);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 3/4
         * of a 24-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>,
         * based on a mil being 24 minutes, and is calculated as 18 + 2 + 4 for a total of 24 minutes. It is the
         * sun's position at {@link #ZENITH_5_POINT_88 5.88&deg;} below the western horizon. This is a very early
         * <em>zman</em> and should not be relied on without Rabbinical guidance.
         * 
         * @todo Additional detailed documentation needed.
         * @return the <code>Date</code> representing the time when the sun is 5.88&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #ZENITH_5_POINT_88
         */
        public Date getTzaisGeonim5Point88Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_5_POINT_88);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 3/4
         * of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> based on the
         * sun's position at {@link #ZENITH_4_POINT_8 4.8&deg;} below the western horizon. This is based on Rabbi Leo Levi's
         * calculations. This is a very early <em>zman</em> and should not be relied on without Rabbinical guidance.
         * @todo Additional documentation needed.
         * 
         * @return the <code>Date</code> representing the time when the sun is 4.8&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #ZENITH_4_POINT_8
         */
        public Date getTzaisGeonim4Point8Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_4_POINT_8);
        }
        
        
        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> as calculated by
         * <a href="https://en.wikipedia.org/wiki/Yechiel_Michel_Tucazinsky">Rabbi Yechiel Michel Tucazinsky</a>. It is
         * based on of the position of the sun no later than {@link #getTzaisGeonim6Point45Degrees() 31 minutes} after sunset
         * in Jerusalem the height of the summer solstice and is 28 minutes after <em>shkiah</em> <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>. This
         * computes to 6.45&deg; below the western horizon.
         * @todo Additional documentation details needed.
         * 
         * @return the <code>Date</code> representing the time when the sun is 6.45&deg; below sea level. If the
         *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
         *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
         *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_6_POINT_45
         */
        public Date getTzaisGeonim6Point45Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_6_POINT_45);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated when the
         * sun's position {@link #ZENITH_7_POINT_083 7.083&deg; (or 7&deg; 5\u2032}) below the western horizon. This is often
         * referred to as 7&deg;5' or 7&deg; and 5 minutes. This calculation is based on the observation of 3 medium-sized
         * stars by Dr. Baruch (Berthold) Cohn in his <em>luach</em> <a href=
         * "https://sammlungen.ub.uni-frankfurt.de/freimann/content/titleinfo/983088">Tabellen enthaltend die Zeitangaben für
         * den Beginn der Nacht und des Tages für die Breitengrade + 66 bis -38</a> published in Strasbourg, France in 1899.
         * This calendar was very popular in Europe, and many other calendars based their time on it. <a href=
         * "https://en.wikipedia.org/wiki/David_Zvi_Hoffmann">Rav Dovid Tzvi Hoffman</a> in his
         * <a href="https://hebrewbooks.org/1053">Sh"Ut Melamed Leho'il</a> in an exchange of letters with Baruch Cohn in <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=1053&st=&pgnum=37">Orach Chaim 30</a> agreed to this <em>zman</em> (page 36),
         * as did the Sh"Ut Bnei Tziyon and the Tenuvas Sadeh. It is very close to the time of the <a href=
         * "https://hebrewbooks.org/22044">Mekor Chesed</a> of the Sefer chasidim. It is close to the position of the sun 30 minutes
         * after sunset in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, but not
         * Exactly. The actual position of the sun 30 minutes after sunset in Jerusalem at the equilux is 7.205&deg; and 7.199&deg;
         * at the equinox. See Hazmanim Bahalacha vol 2, pages 520-521 for more details.
         * 
         * @return the <code>Date</code> representing the time when the sun is 7.083&deg; below sea level. If the
         *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
         *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
         *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_7_POINT_083
         */
        public Date getTzaisGeonim7Point083Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_7_POINT_083);
        }
        
        /**
         * This method returns <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 45 minutes
         * after sunset during the summer solstice in New York, when the <em>neshef</em> (twilight) is the longest. The sun's
         * position at this time computes to {@link #ZENITH_7_POINT_67 7.75&deg;} below the western horizon. See <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=921&pgnum=149">Igros Moshe Even Haezer 4, Ch. 4</a> (regarding
         * <em>tzais</em> for <em>krias Shema</em>). It is also mentioned in Rabbi Heber's <a href=
         * "https://hebrewbooks.org/53000">Shaarei Zmanim</a> on in
         * <a href="https://hebrewbooks.org/pdfpager.aspx?req=53055&pgnum=101">chapter 10 (page 87)</a> and
         * <a href="https://hebrewbooks.org/pdfpager.aspx?req=53055&pgnum=122">chapter 12 (page 108)</a>. Also see the
         * time of 45 minutes in <a href="https://en.wikipedia.org/wiki/Simcha_Bunim_Cohen">Rabbi Simcha Bunim Cohen's</a> <a
         * href="https://www.worldcat.org/oclc/179728985">The radiance of Shabbos</a> as the earliest <em>zman</em> for New York.
         * This <em>zman</em> is also listed in the <a href="https://hebrewbooks.org/pdfpager.aspx?req=1927&pgnum=90">Divrei
         * Shalom Vol. III, chapter 75</a>, and <a href="https://hebrewbooks.org/pdfpager.aspx?req=892&pgnum=431">Bais Av"i
         * Vol. III, chapter 117</a>. This <em>zman</em> is also listed in the Divrei Shalom etc. chapter 177 (FIXME - could not
         * be located). Since this <em>zman</em> depends on the level of light, Rabbi Yaakov Shakow presented this degree-based
         * calculation to Rabbi <a href="https://en.wikipedia.org/wiki/Shmuel_Kamenetsky">Rabbi Shmuel Kamenetsky</a> who agreed
         * to it.
         * @todo add hyperlinks to source of Divrei Shalom once it is located.
         * @return the <code>Date</code> representing the time when the sun is 7.67&deg; below sea level. If the
         *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
         *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
         *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_7_POINT_67
         */
        public Date getTzaisGeonim7Point67Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_7_POINT_67);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated at the
         * sun's position at {@link #ZENITH_8_POINT_5 8.5&deg;} below the western horizon.
         * 
         * @return the <code>Date</code> representing the time when the sun is 8.5&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #ZENITH_8_POINT_5
         */
        public Date getTzaisGeonim8Point5Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_8_POINT_5);
        }
        
        /**
         * This method returns the <em>tzais</em> (nightfall) based on the calculations used in the <a href=
         * "https://www.worldcat.org/oclc/243303103">Luach Itim Lebinah</a> as the stringent time for <em>tzais</em>.  It is
         * calculated at the sun's position at {@link #ZENITH_9_POINT_3 9.3&deg;} below the western horizon.
         * 
         * @return the <code>Date</code> representing the time when the sun is 9.3&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         */
        public Date getTzaisGeonim9Point3Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_9_POINT_3);
        }
        
        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 60
         * minutes after sunset <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, the
         * day that a solar hour is 60 minutes in New York. The sun's position at this time computes to
         * {@link #ZENITH_9_POINT_75 9.75&deg;} below the western horizon. This is the opinion of <a href=
         * "https://en.wikipedia.org/wiki/Yosef_Eliyahu_Henkin">Rabbi Eliyahu Henkin</a>.  This also follows the opinion of
         * <a href="https://en.wikipedia.org/wiki/Shmuel_Kamenetsky">Rabbi Shmuel Kamenetsky</a>. Rabbi Yaakov Shakow presented
         * these degree-based times to Rabbi Shmuel Kamenetsky who agreed to them.
         * 
         * @todo recalculate based on equinox / equilux.
         * @return the <code>Date</code> representing the time when the sun is 9.75&deg; below sea level. If the calculation
         *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
         *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         *
         * @see #getTzais60()
         */
        public Date getTzaisGeonim9Point75Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_9_POINT_75);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Yair_Bacharach">Chavas Yair</a> and <a href=
         * "https://he.wikipedia.org/wiki/%D7%9E%D7%9C%D7%9B%D7%99%D7%90%D7%9C_%D7%A6%D7%91%D7%99_%D7%98%D7%A0%D7%A0%D7%91%D7%95%D7%99%D7%9D"
         * >Divrei Malkiel</a> that the time to walk the distance of a <a href=
         * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> is 15 minutes, for a total of 60 minutes
         * for 4 mil after {@link #getSeaLevelSunset() sea level sunset}. See detailed documentation explaining the 60 minute concept at
         * {@link #getAlos60()}.
         * 
         * @return the <code>Date</code> representing 60 minutes after sea level sunset. If the calculation can't be
         *         computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise,
         *         and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getAlos60()
         * @see #getPlagHamincha60Minutes()
         * @see #getShaahZmanis60Minutes()
         */
        public Date getTzais60() {
                return getTimeOffset(getElevationAdjustedSunset(), 60 * MINUTE_MILLIS);
        }

        /**
         * This method returns <em>tzais</em> usually calculated as 40 minutes (configurable to any offset via
         * {@link #setAteretTorahSunsetOffset(double)}) after sunset. Please note that <em>Chacham</em> Yosef Harari-Raful
         * of Yeshivat Ateret Torah who uses this time, does so only for calculating various other <em>zmanei hayom</em>
         * such as <em>Sof Zman Krias Shema</em> and <em>Plag Hamincha</em>. His calendars do not publish a <em>zman</em>
         * for <em>Tzais</em>. It should also be noted that <em>Chacham</em> Harari-Raful provided a 25 minute <em>zman</em>
         * for Israel. This API uses 40 minutes year round in any place on the globe by default. This offset can be changed
         *  by calling {@link #setAteretTorahSunsetOffset(double)}.
         * 
         * @return the <code>Date</code> representing 40 minutes (configurable via {@link #setAteretTorahSunsetOffset})
         *         after sea level sunset. If the calculation can't be computed such as in the Arctic Circle where there is
         *         at least one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will
         *         be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         */
        public Date getTzaisAteretTorah() {
                return getTimeOffset(getElevationAdjustedSunset(), getAteretTorahSunsetOffset() * MINUTE_MILLIS);
        }

        /**
         * Returns the offset in minutes after sunset used to calculate <em>tzais</em> based on the calculations of
         * <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah calculations. The default value is 40 minutes.
         * This affects most <em>zmanim</em>, since almost all zmanim use subset as part of their calculation.
         * 
         * @return the number of minutes after sunset for <em>Tzait</em>.
         * @see #setAteretTorahSunsetOffset(double)
         */
        public double getAteretTorahSunsetOffset() {
                return ateretTorahSunsetOffset;
        }

        /**
         * Allows setting the offset in minutes after sunset for the Ateret Torah <em>zmanim</em>. The default if unset is
         * 40 minutes. <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah uses 40 minutes globally with the exception
         * of Israel where a 25-minute offset is used. This 40 minute (or any other) offset can be overridden by this method.
         * This offset impacts all Ateret Torah <em>zmanim</em>.
         * 
         * @param ateretTorahSunsetOffset
         *            the number of minutes after sunset to use as an offset for the Ateret Torah <em>tzais</em>
         * @see #getAteretTorahSunsetOffset()
         */
        public void setAteretTorahSunsetOffset(double ateretTorahSunsetOffset) {
                this.ateretTorahSunsetOffset = ateretTorahSunsetOffset;
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) based on the
         * calculation of <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah, that the day starts
         * {@link #getAlos72Zmanis() 1/10th of the day} before sunrise and is usually calculated as ending
         * {@link #getTzaisAteretTorah() 40 minutes after sunset} (configurable to any offset via
         * {@link #setAteretTorahSunsetOffset(double)}). <em>shaos zmaniyos</em> are calculated based on this day and added
         * to {@link #getAlos72Zmanis() <em>alos</em>} to reach this time. This time is 3
         * {@link #getShaahZmanisAteretTorah() <em>shaos zmaniyos</em>} (temporal hours) after
         * {@link #getAlos72Zmanis() <em>alos</em> 72 <em>zmaniyos</em>}. <b>Note: </b> Based on this calculation <em>chatzos</em>
         * will not be at midday.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em> based on this calculation. If the
         *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where
         *         the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Zmanis()
         * @see #getTzaisAteretTorah()
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         * @see #getShaahZmanisAteretTorah()
         */
        public Date getSofZmanShmaAteretTorah() {
                return getSofZmanShma(getAlos72Zmanis(), getTzaisAteretTorah(), false);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) based on the calculation
         * of <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah, that the day starts {@link #getAlos72Zmanis()
         * 1/10th of the day} before sunrise and is usually calculated as ending {@link #getTzaisAteretTorah() 40 minutes
         * after sunset} (configurable to any offset via {@link #setAteretTorahSunsetOffset(double)}). <em>shaos zmaniyos</em>
         * are calculated based on this day and added to {@link #getAlos72Zmanis() <em>alos</em>} to reach this time. This time
         * is 4 * {@link #getShaahZmanisAteretTorah() <em>shaos zmaniyos</em>} (temporal hours) after
         * {@link #getAlos72Zmanis() <em>alos</em> 72 zmaniyos}.
         * <b>Note: </b> Based on this calculation <em>chatzos</em> will not be at midday.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em> based on this calculation. If the
         *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where
         *         the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Zmanis()
         * @see #getTzaisAteretTorah()
         * @see #getShaahZmanisAteretTorah()
         * @see #setAteretTorahSunsetOffset(double)
         */
        public Date getSofZmanTfilaAteretTorah() {
                return getSofZmanTfila(getAlos72Zmanis(), getTzaisAteretTorah(), false);
        }
        
        /**
         * @see #getSofZmanTfilaAteretTorah()
         * @deprecated misspelled method name (all other methods spell tfila without an H) to be removed in 3.0.0.
         * @return the <code>Date</code> of the latest <em>zman krias shema</em> based on this calculation. If the
         *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where
         *         the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getSofZmanTfilahAteretTorah() {
                return getSofZmanTfila(getAlos72Zmanis(), getTzaisAteretTorah(), false);
        }

        /**
         * This method returns the time of <em>mincha gedola</em> based on the calculation of <em>Chacham</em> Yosef
         * Harari-Raful of Yeshivat Ateret Torah, that the day starts {@link #getAlos72Zmanis() 1/10th of the day}
         * before sunrise and is usually calculated as ending {@link #getTzaisAteretTorah() 40 minutes after sunset}
         * (configurable to any offset via {@link #setAteretTorahSunsetOffset(double)}). This is the preferred earliest
         * time to pray <em>mincha</em> according to the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides"
         * >Rambam</a> and others. For more information on this see the documentation on {@link #getMinchaGedola() <em>mincha
         * gedola</em>}. This is calculated as 6.5 {@link #getShaahZmanisAteretTorah()  solar hours} after <em>alos</em>. The
         * calculation used is 6.5 * {@link #getShaahZmanisAteretTorah()} after {@link #getAlos72Zmanis() <em>alos</em>}.
         * 
         * @see #getAlos72Zmanis()
         * @see #getTzaisAteretTorah()
         * @see #getShaahZmanisAteretTorah()
         * @see #getMinchaGedola()
         * @see #getMinchaKetanaAteretTorah()
         * @see ZmanimCalendar#getMinchaGedola()
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         * 
         * @return the <code>Date</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaGedolaAteretTorah() {
                return getMinchaGedola(getAlos72Zmanis(), getTzaisAteretTorah(), false);
        }

        /**
         * This method returns the time of <em>mincha ketana</em> based on the calculation of
         * <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah, that the day starts
         * {@link #getAlos72Zmanis() 1/10th of the day} before sunrise and is usually calculated as ending
         * {@link #getTzaisAteretTorah() 40 minutes after sunset} (configurable to any offset via
         * {@link #setAteretTorahSunsetOffset(double)}). This is the preferred earliest time to pray <em>mincha</em>
         * according to the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others.
         * For more information on this see the documentation on {@link #getMinchaGedola() <em>mincha gedola</em>}. This is
         * calculated as 9.5 {@link #getShaahZmanisAteretTorah() solar hours} after {@link #getAlos72Zmanis() <em>alos</em>}.
         * The calculation used is 9.5 * {@link #getShaahZmanisAteretTorah()} after {@link #getAlos72Zmanis() <em>alos</em>}.
         * 
         * @see #getAlos72Zmanis()
         * @see #getTzaisAteretTorah()
         * @see #getShaahZmanisAteretTorah()
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         * @see #getMinchaGedola()
         * @see #getMinchaKetana()
         * @return the <code>Date</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaKetanaAteretTorah() {
                return getMinchaKetana(getAlos72Zmanis(), getTzaisAteretTorah(), false);
        }

        /**
         * This method returns the time of <em>plag hamincha</em> based on the calculation of <em>Chacham</em> Yosef Harari-Raful
         * of Yeshivat Ateret Torah, that the day starts {@link #getAlos72Zmanis() 1/10th of the day} before sunrise and is
         * usually calculated as ending {@link #getTzaisAteretTorah() 40 minutes after sunset} (configurable to any offset
         * via {@link #setAteretTorahSunsetOffset(double)}). <em>shaos zmaniyos</em> are calculated based on this day and
         * added to {@link #getAlos72Zmanis() <em>alos</em>} to reach this time. This time is 10.75
         * {@link #getShaahZmanisAteretTorah() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Zmanis()
         * dawn}.
         * 
         * @return the <code>Date</code> of the <em>plag</em>. If the calculation can't be computed such as in the Arctic Circle
         *         where there is at least one day a year where the sun does not rise, and one where it does not set, a null
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Zmanis()
         * @see #getTzaisAteretTorah()
         * @see #getShaahZmanisAteretTorah()
         * @see #setAteretTorahSunsetOffset(double)
         * @see #getAteretTorahSunsetOffset()
         */
        public Date getPlagHaminchaAteretTorah() {
                return getPlagHamincha(getAlos72Zmanis(), getTzaisAteretTorah(), false);
        }

        /**
         * Method to return <em>tzais</em> (dusk) calculated as 72 minutes zmaniyos, or 1/10th of the day after
         * {@link #getSeaLevelSunset() sea level sunset}. This is the way that the <a href=
         * "https://en.wikipedia.org/wiki/Abraham_Cohen_Pimentel">Minchas Cohen</a> in Ma'amar 2:4 calculates Rebbeinu Tam's
         * time of <em>tzeis</em>. It should be noted that this calculation results in the shortest time from sunset to
         * <em>tzais</em> being during the winter solstice, the longest at the summer solstice and 72 clock minutes at the
         * equinox. This does not match reality, since there is no direct relationship between the length of the day and
         * twilight. The shortest twilight is during the equinox, the longest is during the summer solstice, and in the
         * winter with the shortest daylight, the twilight period is longer than during the equinoxes.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos72Zmanis()
         */
        public Date getTzais72Zmanis() {
                return getZmanisBasedOffset(1.2);
        }
        
        /**
         * A utility method to return <em>alos</em> (dawn) or <em>tzais</em> (dusk) based on a fractional day offset.
         * @param hours the number of <em>shaos zmaniyos</em> (temporal hours) before sunrise or after sunset that defines dawn
         *        or dusk. If a negative number is passed in, it will return the time of <em>alos</em> (dawn) (subtracting the
         *        time from sunrise) and if a positive number is passed in, it will return the time of <em>tzais</em> (dusk)
         *        (adding the time to sunset). If 0 is passed in, a <code>null</code> will be returned (since we can't tell if it
         *        is sunrise or sunset based).
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. A <code>null</code> will also be returned if 0 is passed in, since we can't
         *         tell if it is sunrise or sunset based. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         */
        private Date getZmanisBasedOffset(double hours) {
                long shaahZmanis = getShaahZmanisGra();
                if (shaahZmanis == Long.MIN_VALUE || hours == 0) {
                        return null;
                }

                if (hours > 0) {
                        return getTimeOffset(getElevationAdjustedSunset(), (long) (shaahZmanis * hours));
                } else {
                        return getTimeOffset(getElevationAdjustedSunrise(), (long) (shaahZmanis * hours));
                }
        }

        /**
         * Method to return <em>tzais</em> (dusk) calculated using 90 minutes zmaniyos or 1/8th of the day after {@link
         * #getSeaLevelSunset() sea level sunset}. This time is known in Yiddish as the <em>achtel</em> (an eighth)
         * <em>zman</em>.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos90Zmanis()
         */
        public Date getTzais90Zmanis() {
                return getZmanisBasedOffset(1.5);
        }

        /**
         * Method to return <em>tzais</em> (dusk) calculated using 96 minutes <em>zmaniyos</em> or 1/7.5 of the day after
         * {@link #getSeaLevelSunset() sea level sunset}.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos96Zmanis()
         */
        public Date getTzais96Zmanis() {
                return getZmanisBasedOffset(1.6);
        }

        /**
         * Method to return <em>tzais</em> (dusk) calculated as 90 minutes after sea level sunset. This method returns
         * <em>tzais</em> (nightfall) based on the opinion of the Magen Avraham that the time to walk the distance of a
         * <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> according to the
         * <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a>'s opinion is 18 minutes, for a total of 90
         * minutes based on the opinion of Ula who calculated <em>tzais</em> as 5 mil after sea level
         * <em>shkiah</em> (sunset). A similar calculation {@link #getTzais19Point8Degrees()} uses solar position
         * calculations based on this time.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getTzais19Point8Degrees()
         * @see #getAlos90()
         */
        public Date getTzais90() {
                return getTimeOffset(getElevationAdjustedSunset(), 90 * MINUTE_MILLIS);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns <em>tzais</em> (nightfall) based on the calculations
         * of <a href="https://en.wikipedia.org/wiki/Avraham_Chaim_Naeh">Rav Chaim Naeh</a> that the time to walk the
         * distance of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>
         * according to the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a>'s opinion is 2/5 of an hour (24 minutes)
         * for a total of 120 minutes based on the opinion of <em>Ula</em> who calculated <em>tzais</em> as 5 mil after
         * sea level <em>shkiah</em> (sunset). A similar calculation {@link #getTzais26Degrees()} uses degree-based calculations
         * based on this 120 minute calculation. Since the <em>zman</em> is extremely late and at a point that is long past the
         * 18&deg; point where the darkest point is reached, it should only be used <em>lechumra</em>, such as delaying the start
         * of nighttime <em>mitzvos</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time, and if used
         *         <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no current plan to remove this
         *         method from the API, and this deprecation is intended to alert developers of the danger of using it.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}.
         *         documentation.
         * @see #getTzais26Degrees()
         * @see #getAlos120()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getTzais120() {
                return getTimeOffset(getElevationAdjustedSunset(), 120 * MINUTE_MILLIS);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns <em>tzais</em> (dusk) calculated using 120 minutes
         * <em>zmaniyos</em> after {@link #getSeaLevelSunset() sea level sunset}. Since the <em>zman</em>
         * is extremely late and at a time when the sun is well below the 18&deg; point (scientifically the darkest point) in
         * most places on the globe, it should only be used <em>lechumra</em>, such as delaying the start of nighttime
         * <em>mitzvos</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time, and if used
         *         <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no current plan to remove this
         *         method from the API, and this deprecation is intended to alert developers of the danger of using it.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos120Zmanis()
         * @see #getTzais120()
         * @see #getTzais26Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getTzais120Zmanis() {
                return getZmanisBasedOffset(2.0);
        }

        /**
         * This calculates the time of <em>tzais</em> at the point when the sun is 16.1&deg; below the horizon. This is
         * the sun's dip below the horizon 72 minutes after sunset according Rabbeinu Tam's calculation of <em>tzais</em>
         * <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> in
         * Jerusalem. The question of equinox VS equilux is complex, with Rabbi Meir Posen in the <a href=
         * "https://www.worldcat.org/oclc/956316270">Ohr Meir</a> of the opinion that the equilux should be used. See
         * Yisrael Vehazmanim vol I, 34:1:4. Rabbi Yedidya Manet in his <a href=
         * "https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei Halacha Lema'aseh</a> (4th edition part 2, pages
         * and 22 and 24) and Rabbi Yonah Metzbuch (in a letter published by Rabbi Manet) are of the opinion that the
         * astronomical equinox should be used. The difference adds up to about 9 seconds, too trivial to make much of a
         * difference. For information on how this is calculated see the comments on {@link #getAlos16Point1Degrees()}.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as northern and
         *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
         *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzais72()
         * @see #getAlos16Point1Degrees() for more information on this calculation.
         */
        public Date getTzais16Point1Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_16_POINT_1);
        }

        /**
         * This method should be used <em>lechumra</em> only and returns <em>tzais</em> based on when the sun is 26&deg;
         * below the horizon.For information on how this is calculated see the comments on {@link #getAlos26Degrees()}.
         * Since the <em>zman</em> is extremely late and at a point when it is long past the 18&deg; point where the
         * darkest point is reached, it should only be used <em>lechumra</em> such as delaying the start of nighttime
         * <em>mitzvos</em>.
         * 
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time, and if used
         *         <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no current plan to remove this
         *         method from the API, and this deprecation is intended to alert developers of the danger of using it.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as northern and
         *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
         *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzais120()
         * @see #getAlos26Degrees()
         */
        @Deprecated // (forRemoval=false) // add back once Java 9 is the minimum supported version
        public Date getTzais26Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_26_DEGREES);
        }

        /**
         * For information on how this is calculated see the comments on {@link #getAlos18Degrees()}
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as northern and
         *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
         *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos18Degrees()
         */
        public Date getTzais18Degrees() {
                return getSunsetOffsetByDegrees(ASTRONOMICAL_ZENITH);
        }

        /**
         * For information on how this is calculated see the comments on {@link #getAlos19Point8Degrees()}
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as northern and
         *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
         *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzais90()
         * @see #getAlos19Point8Degrees()
         */
        public Date getTzais19Point8Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_19_POINT_8);
        }

        /**
         * A method to return <em>tzais</em> (dusk) calculated as 96 minutes after sea level sunset. For information on how
         * this is calculated see the comments on {@link #getAlos96()}.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos96()
         */
        public Date getTzais96() {
                return getTimeOffset(getElevationAdjustedSunset(), 96 * MINUTE_MILLIS);
        }

        /**
         * A method that returns the local time for fixed <em>chatzos</em>. This time is noon and midnight adjusted from
         * standard time to account for the local latitude. The 360&deg; of the globe divided by 24 calculates to 15&deg;
         * per hour with 4 minutes per degree, so at a longitude of 0 , 15, 30 etc... <em>Chatzos</em> is at exactly 12:00
         * noon. This is the time of <em>chatzos</em> according to the <a href=
         * "https://en.wikipedia.org/wiki/Aruch_HaShulchan">Aruch Hashulchan</a> in <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=7705&pgnum=426">Orach Chaim 233:14</a> and <a href=
         * "https://en.wikipedia.org/wiki/Moshe_Feinstein">Rabbi Moshe Feinstein</a> in Igros Moshe <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=916&st=&pgnum=67">Orach Chaim 1:24</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=14675&pgnum=191">2:20</a>.
         * Lakewood, N.J., with a longitude of -74.222, is 0.778 away from the closest multiple of 15 at -75&deg;. This
         * is multiplied by 4 to yield 3 minutes and 7 seconds for a <em>chatzos</em> of 11:56:53. This method is not tied
         * to the theoretical 15&deg; timezones, but will adjust to the actual timezone and <a
         * href="https://en.wikipedia.org/wiki/Daylight_saving_time">Daylight saving time</a>.
         * 
         * @return the Date representing the local <em>chatzos</em>
         * @see GeoLocation#getLocalMeanTimeOffset()
         * @see AstronomicalCalendar#getLocalMeanTime(double)
         */
        public Date getFixedLocalChatzos() {
                return getLocalMeanTime(12.0);
        }

        /**
         * A method that returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) calculated as 3
         * clock hours before {@link #getFixedLocalChatzos()}. Note that there are opinions brought down in Yisrael Vehazmanim
         * <a href="https://hebrewbooks.org/pdfpager.aspx?req=9765&st=&pgnum=85">page 57</a> and Rav Yitzchak Silber's <a href=
         * "https://www.worldcat.org/oclc/811253716">Shaos Shavos Bahalacha</a> that this calculation is a mistake and regular
         * <em>chatzos</em> should be used for clock-hour calculations as opposed to fixed local <em>chatzos</em>. According to
         * these opinions it should be 3 clock hours before regular <em>chatzos</em> as calculated in {@link
         * #getSofZmanShma3HoursBeforeChatzos()}.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em> calculated as 3 clock hours before
         *         {@link #getFixedLocalChatzos()}.
         * @see #getFixedLocalChatzos()
         * @see #getSofZmanShma3HoursBeforeChatzos()
         * @see #getSofZmanTfilaFixedLocal()
         *         
         * @deprecated This method of calculating <em>sof zman Shma</em> is considered a mistaken understanding of the proper
         *         calculation of this <em>zman</em> in the opinion of Rav Yitzchak Silber's <a href=
         *         "https://www.worldcat.org/oclc/811253716">Sha'aos Shavos Bahalacha</a>. On pages 316-318 he discusses Rav Yisrael
         *         Harfenes's calculations and points to his seeming agreement that using fixed local <em>chatzos</em> as the focal
         *         point is problematic. See Yisrael Vehazmanim <a href=
         *         "https://hebrewbooks.org/pdfpager.aspx?req=9765&st=&pgnum=85">page 57</a>. While the Yisrael Vehazmanim mentions
         *         this issue in vol. 1, it was not corrected in the calculations in vol. 3 and other parts of the <em>sefer</em>.
         *         A competent rabbinical authority should be consulted before using this <em>zman</em>. Instead, the use of {@link
         *         #getSofZmanShma3HoursBeforeChatzos()} should be used to calculate <em>sof zman Tfila</em> using 3 fixed clock hours.
         *         This will likely be removed in v3.0.
         */
        @Deprecated // (since="2.4.0", forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getSofZmanShmaFixedLocal() {
                return getTimeOffset(getFixedLocalChatzos(), -180 * MINUTE_MILLIS);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) calculated as 2 hours
         * before {@link #getFixedLocalChatzos()}. See the documentation on {@link #getSofZmanShmaFixedLocal()} showing
         * differing opinions on how the <em>zman</em> is calculated. According to many opinions {@link
         * #getSofZmanTfila2HoursBeforeChatzos()} should be used as opposed to this <em>zman</em>.
         * 
         * @return the <code>Date</code> of the latest <em>zman tfila</em>.
         * @see #getFixedLocalChatzos()
         * @see #getSofZmanShmaFixedLocal()
         * @see #getSofZmanTfila2HoursBeforeChatzos()
         *         
         * @deprecated This method of calculating <em>sof zman Tfila</em> is considered a mistaken understanding of the proper
         *         calculation of this <em>zman</em> in the opinion of Rav Yitzchak Silber's <a href=
         *         "https://www.worldcat.org/oclc/811253716">Sha'aos Shavos Bahalacha</a>. On pages 316-318 he discusses Rav Yisrael
         *         Harfenes's calculations and points to his seeming agreement that using fixed local <em>chatzos</em> as the focal
         *         point is problematic. See Yisrael Vehazmanim <a href=
         *         "https://hebrewbooks.org/pdfpager.aspx?req=9765&st=&pgnum=85">page 57</a>. While the Yisrael Vehazmanim mentions
         *         this issue in vol. 1, it was not corrected in the calculations in vol. 3 and other parts of the <em>sefer</em>.
         *         A competent rabbinical authority should be consulted before using this <em>zman</em>. Instead, the use of {@link
         *         #getSofZmanTfila2HoursBeforeChatzos()} should be used to calculate <em>sof zman Tfila</em> using 2 fixed
         *         clock hours. This will likely be removed in v3.0.
         */
        @Deprecated // (since="2.4.0", forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getSofZmanTfilaFixedLocal() {
                return getTimeOffset(getFixedLocalChatzos(), -120 * MINUTE_MILLIS);
        }

        /**
         * Returns the latest time of <em>Kidush Levana</em> according to the <a
         * href="https://en.wikipedia.org/wiki/Yaakov_ben_Moshe_Levi_Moelin">Maharil's</a> opinion that it is calculated as
         * halfway between <em>molad</em> and <em>molad</em>. This adds half the 29 days, 12 hours and 793 chalakim time
         * between <em>molad</em> and <em>molad</em> (14 days, 18 hours, 22 minutes and 666 milliseconds) to the month's <em>molad</em>.
         * If the time of <em>sof zman Kiddush Levana</em> occurs during the day (between the <em>alos</em> and <em>tzais</em> passed in
         * as parameters), it returns the <em>alos</em> passed in. If a <code>null</code> <em>alos</em> or <em>tzais</em> are passed to
         * this method, the non-daytime adjusted time will be returned.
         * 
         * @param alos
         *            the beginning of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and
         *            ending at <em>tzais</em>), the time returned will be <em>alos</em>. If either the <em>alos</em> or <em>tzais</em>
         *            parameters are null, no daytime adjustment will be made.
         * @param tzais
         *            the end of the Jewish day. If Kidush Levana occurs during the day (starting at <em>alos</em> and ending at
         *            <em>tzais</em>), the time returned will be <em>alos</em>. If either the <em>alos</em> or <em>tzais</em> parameter
         *            are null, no daytime adjustment will be made.
         * @return the Date representing the moment halfway between molad and molad. If the time occurs between
         *         <em>alos</em> and <em>tzais</em>, <em>alos</em> will be returned. If the <em>zman</em> will not occur on this day, a
         *         <code>null</code> will be returned.
         * @see #getSofZmanKidushLevanaBetweenMoldos()
         * @see #getSofZmanKidushLevana15Days(Date, Date)
         * @see JewishCalendar#getSofZmanKidushLevanaBetweenMoldos()
         */
        public Date getSofZmanKidushLevanaBetweenMoldos(Date alos, Date tzais) {
                JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));

                // Do not calculate for impossible dates, but account for extreme cases. In the extreme case of Rapa Iti in French
                // Polynesia on Dec 2027 when kiddush Levana 3 days can be said on <em>Rosh Chodesh</em>, the sof zman Kiddush Levana
                // will be on the 12th of the Teves. In the case of Anadyr, Russia on Jan, 2071, sof zman Kiddush Levana between the
                // moldos will occur is on the night of 17th of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
                if (jewishCalendar.getJewishDayOfMonth() < 11 || jewishCalendar.getJewishDayOfMonth() > 16) { 
                        return null;
                }
                return getMoladBasedTime(jewishCalendar.getSofZmanKidushLevanaBetweenMoldos(), alos, tzais, false);
        }
        
        /**
         * Returns the Date of the <em>molad</em> based time if it occurs on the current date. Since <em>Kiddush Levana</em>
         * can only be said during the day, there are parameters to limit it to between <em>alos</em> and <em>tzais</em>. If
         * the time occurs between <em>alos</em> and <em>tzais</em>, <em>tzais</em> will be returned.
         * 
         * @param moladBasedTime
         *            the <em>molad</em> based time such as <em>molad</em>, <em>tchilas</em> and <em>sof zman Kiddush Levana</em>
         * @param alos
         *            optional start of day to limit <em>molad</em> times to the end of the night before or beginning of the next night.
         *            Ignored if either <em>alos</em> or <em>tzais</em> are null.
         * @param tzais
         *            optional end of day to limit <em>molad</em> times to the end of the night before or beginning of the next night.
         *            Ignored if either <em>tzais</em> or <em>alos</em> are null
         * @param techila
         *            is it the start of <em>Kiddush Levana</em> time or the end? If it is start roll it to the next <em>tzais</em>, and
         *            and if it is the end, return the end of the previous night (<em>alos</em> passed in). Ignored if either
         *            <em>alos</em> or <em>tzais</em> are null.
         * @return the <em>molad</em> based time. If the <em>zman</em> does not occur during the current date, <code>null</code> will be
         *         returned.
         */
        private Date getMoladBasedTime(Date moladBasedTime, Date alos, Date tzais, boolean techila) {
                Date lastMidnight = getMidnightLastNight();
                Date midnightTonight = getMidnightTonight();
                if (!(moladBasedTime.before(lastMidnight) || moladBasedTime.after(midnightTonight))){
                        if (alos != null || tzais != null) {
                                if (techila && !(moladBasedTime.before(tzais) || moladBasedTime.after(alos))){
                                        return tzais;
                                } else {
                                        return alos;
                                }
                        }
                        return moladBasedTime;
                }
                return null;
        }

        /**
         * Returns the latest time of Kiddush Levana according to the <a
         * href="https://en.wikipedia.org/wiki/Yaakov_ben_Moshe_Levi_Moelin">Maharil's</a> opinion that it is calculated as
         * halfway between <em>molad</em> and <em>molad</em>. This adds half the 29 days, 12 hours and 793 chalakim time between
         * <em>molad</em> and <em>molad</em> (14 days, 18 hours, 22 minutes and 666 milliseconds) to the month's <em>molad</em>.
         * The <em>sof zman Kiddush Levana</em> will be returned even if it occurs during the day. To limit the time to between
         * <em>tzais</em> and <em>alos</em>, see {@link #getSofZmanKidushLevanaBetweenMoldos(Date, Date)}.
         * 
         * @return the Date representing the moment halfway between molad and molad. If the time occurs between
         *         <em>alos</em> and <em>tzais</em>, <em>alos</em> will be returned. If the <em>zman</em> will not occur on this
         *         day, a <code>null</code> will be returned.
         * @see #getSofZmanKidushLevanaBetweenMoldos(Date, Date)
         * @see #getSofZmanKidushLevana15Days()
         * @see JewishCalendar#getSofZmanKidushLevanaBetweenMoldos()
         */
        public Date getSofZmanKidushLevanaBetweenMoldos() {
                return getSofZmanKidushLevanaBetweenMoldos(null, null); 
        }

        /**
         * Returns the latest time of <em>Kiddush Levana</em> calculated as 15 days after the <em>molad</em>. This is the
         * opinion brought down in the Shulchan Aruch (Orach Chaim 426). It should be noted that some opinions hold that the
         * <a href="https://en.wikipedia.org/wiki/Moses_Isserles">Rema</a> who brings down the opinion of the <a
         * href="https://en.wikipedia.org/wiki/Yaakov_ben_Moshe_Levi_Moelin">Maharil's</a> of calculating
         * {@link #getSofZmanKidushLevanaBetweenMoldos(Date, Date) half way between <em>molad</em> and <em>molad</em>} is of
         * the opinion that the Mechaber agrees to his opinion. Also see the Aruch Hashulchan. For additional details on the subject,
         * see Rabbi Dovid Heber's very detailed write-up in <em>Siman Daled</em> (chapter 4) of <a href=
         * "https://hebrewbooks.org/53000">Shaarei Zmanim</a>. If the time of <em>sof zman Kiddush Levana</em> occurs during
         * the day (between the <em>alos</em> and <em>tzais</em> passed in as parameters), it returns the <em>alos</em> passed in. If a
         * null <em>alos</em> or <em>tzais</em> are passed to this method, the non-daytime adjusted time will be returned.
         * 
         * @param alos
         *            the beginning of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and
         *            ending at <em>tzais</em>), the time returned will be <em>alos</em>. If either the <em>alos</em> or <em>tzais</em>
         *            parameters are null, no daytime adjustment will be made.
         * @param tzais
         *            the end of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and ending at
         *            <em>tzais</em>), the time returned will be <em>alos</em>. If either the <em>alos</em> or <em>tzais</em> parameters
         *            are null, no daytime adjustment will be made.
         *
         * @return the Date representing the moment 15 days after the molad. If the time occurs between <em>alos</em> and
         *         <em>tzais</em>, <em>alos</em> will be returned. If the <em>zman</em> will not occur on this day, a
         *         <code>null</code> will be returned.
         * 
         * @see #getSofZmanKidushLevanaBetweenMoldos(Date, Date)
         * @see JewishCalendar#getSofZmanKidushLevana15Days()
         */
        public Date getSofZmanKidushLevana15Days(Date alos, Date tzais) {
                JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                // Do not calculate for impossible dates, but account for extreme cases. In the extreme case of Rapa Iti in
                // French Polynesia on Dec 2027 when kiddush Levana 3 days can be said on <em>Rosh Chodesh</em>, the sof zman Kiddush
                // Levana will be on the 12th of the Teves. in the case of Anadyr, Russia on Jan, 2071, sof zman kiddush levana will
                // occur after midnight on the 17th of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
                if (jewishCalendar.getJewishDayOfMonth() < 11 || jewishCalendar.getJewishDayOfMonth() > 17) {
                        return null;
                }
                return getMoladBasedTime(jewishCalendar.getSofZmanKidushLevana15Days(), alos, tzais, false);
        }

        /**
         * Returns the latest time of <em>Kiddush Levana</em> calculated as 15 days after the molad. This is the opinion of
         * the Shulchan Aruch (Orach Chaim 426). It should be noted that some opinions hold that the
         * <a href="https://en.wikipedia.org/wiki/Moses_Isserles">Rema</a> who brings down the opinion of the <a
         * href="https://en.wikipedia.org/wiki/Yaakov_ben_Moshe_Levi_Moelin">Maharil's</a> of calculating
         * {@link #getSofZmanKidushLevanaBetweenMoldos(Date, Date) half way between <em>molad</em> and <em>molad</em>} is of
         * the opinion that the Mechaber agrees to his opinion. Also see the Aruch Hashulchan. For additional details on the subject,
         * See Rabbi Dovid Heber's very detailed write-up in Siman Daled (chapter 4) of <a href="https://hebrewbooks.org/53000">Shaarei
         * Zmanim</a>. The <em>sof zman Kiddush Levana</em> will be returned even if it occurs during the day. To limit the time to
         * between <em>tzais</em> and <em>alos</em>, see {@link #getSofZmanKidushLevana15Days(Date, Date)}.
         * 
         * @return the Date representing the moment 15 days after the <em>molad</em>. If the time occurs between
         *         <em>alos</em> and <em>tzais</em>, <em>alos</em> will be returned. If the <em>zman</em> will not occur on this day, a
         *         <code>null</code> will be returned.
         * 
         * @see #getSofZmanKidushLevana15Days(Date, Date)
         * @see #getSofZmanKidushLevanaBetweenMoldos()
         * @see JewishCalendar#getSofZmanKidushLevana15Days()
         * 
         */
        public Date getSofZmanKidushLevana15Days() {
                return getSofZmanKidushLevana15Days(null, null);
        }
        
        /**
         * Returns the earliest time of <em>Kiddush Levana</em> according to <a href=
         * "https://en.wikipedia.org/wiki/Yonah_Gerondi">Rabbeinu Yonah</a>'s opinion that it can be said 3 days after the
         * <em>molad</em>. The time will be returned even if it occurs during the day when <em>Kiddush Levana</em> can't be said.
         * Use {@link #getTchilasZmanKidushLevana3Days(Date, Date)} if you want to limit the time to night hours.
         * 
         * @return the Date representing the moment 3 days after the molad. If the <em>zman</em> will not occur on this day, a
         *         <code>null</code> will be returned.
         * @see #getTchilasZmanKidushLevana3Days(Date, Date)
         * @see #getTchilasZmanKidushLevana7Days()
         * @see JewishCalendar#getTchilasZmanKidushLevana3Days()
         */
        public Date getTchilasZmanKidushLevana3Days() {
                return getTchilasZmanKidushLevana3Days(null, null);
        }

        /**
         * Returns the earliest time of <em>Kiddush Levana</em> according to <a href=
         * "https://en.wikipedia.org/wiki/Yonah_Gerondi">Rabbeinu Yonah</a>'s opinion that it can be said 3 days after the <em>molad</em>.
         * If the time of <em>tchilas zman Kiddush Levana</em> occurs during the day (between <em>alos</em> and <em>tzais</em> passed to
         * this method) it will return the following <em>tzais</em>. If null is passed for either <em>alos</em> or <em>tzais</em>, the actual
         * <em>tchilas zman Kiddush Levana</em> will be returned, regardless of if it is during the day or not.
         * 
         * @param alos
         *            the beginning of the Jewish day. If Kidush Levana occurs during the day (starting at <em>alos</em> and ending
         *            at <em>tzais</em>), the time returned will be <em>tzais</em>. If either the <em>alos</em> or <em>tzais</em> parameters
         *            are null, no daytime adjustment will be made.
         * @param tzais
         *            the end of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and ending at
         *            <em>tzais</em>), the time returned will be <em>tzais</em>. If either the <em>alos</em> or <em>tzais</em> parameters
         *            are null, no daytime adjustment will be made.
         *
         * @return the Date representing the moment 3 days after the molad. If the time occurs between <em>alos</em> and
         *         <em>tzais</em>, <em>tzais</em> will be returned. If the <em>zman</em> will not occur on this day, a
         *         <code>null</code> will be returned.
         * @see #getTchilasZmanKidushLevana3Days()
         * @see #getTchilasZmanKidushLevana7Days(Date, Date)
         * @see JewishCalendar#getTchilasZmanKidushLevana3Days()
         */
        public Date getTchilasZmanKidushLevana3Days(Date alos, Date tzais) {
                JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                
                // Do not calculate for impossible dates, but account for extreme cases. Tchilas zman kiddush Levana 3 days for
                // the extreme case of Rapa Iti in French Polynesia on Dec 2027 when kiddush Levana 3 days can be said on the evening
                // of the 30th, the second night of Rosh Chodesh. The 3rd day after the <em>molad</em> will be on the 4th of the month.
                // In the case of Anadyr, Russia on Jan, 2071, when sof zman kiddush levana is on the 17th of the month, the 3rd day
                // from the molad will be on the 5th day of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
                if (jewishCalendar.getJewishDayOfMonth() > 5 && jewishCalendar.getJewishDayOfMonth() < 30) {
                        return null;
                }
                
                Date zman = getMoladBasedTime(jewishCalendar.getTchilasZmanKidushLevana3Days(), alos, tzais, true);
                
                //Get the following month's zman kiddush Levana for the extreme case of Rapa Iti in French Polynesia on Dec 2027 when
                // kiddush Levana can be said on Rosh Chodesh (the evening of the 30th). See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (page 32)
                if (zman == null && jewishCalendar.getJewishDayOfMonth() == 30) {
                        jewishCalendar.forward(Calendar.MONTH, 1);
                        zman = getMoladBasedTime(jewishCalendar.getTchilasZmanKidushLevana3Days(), null, null, true);
                }
                
                return zman;
        }
        
        /**
         * Returns the point in time of <em>Molad</em> as a <code>Date</code> Object. For the traditional day of week, hour,
         * minute and chalakim, {@link JewishCalendar#getMoladAsDate()} and the not yet completed
         * {@link com.kosherjava.zmanim.hebrewcalendar.HebrewDateFormatter} that will have formatting for this.
         * 
         * @return the Date representing the moment of the molad. If the <em>molad</em> does not occur on this day, a
         *         <code>null</code> will be returned.
         * 
         * @see #getTchilasZmanKidushLevana3Days()
         * @see #getTchilasZmanKidushLevana7Days(Date, Date)
         * @see JewishCalendar#getMoladAsDate()
         */
        public Date getZmanMolad() {
                JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                
                // Optimize to not calculate for impossible dates, but account for extreme cases. The molad in the extreme case of Rapa
                // Iti in French Polynesia on Dec 2027 occurs on the night of the 27th of Kislev. In the case of Anadyr, Russia on
                // Jan 2071, the molad will be on the 2nd day of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
                if (jewishCalendar.getJewishDayOfMonth() > 2 && jewishCalendar.getJewishDayOfMonth() < 27) {
                        return null;
                }
                Date molad = getMoladBasedTime(jewishCalendar.getMoladAsDate(), null, null, true);

                // deal with molad that happens on the end of the previous month
                if (molad == null && jewishCalendar.getJewishDayOfMonth() > 26) {
                        jewishCalendar.forward(Calendar.MONTH, 1);
                        molad = getMoladBasedTime(jewishCalendar.getMoladAsDate(), null, null, true);
                }
                return molad;
        }
        
        /**
         * Used by Molad based <em>zmanim</em> to determine if <em>zmanim</em> occur during the current day.
         * @see #getMoladBasedTime(Date, Date, Date, boolean)
         * @return previous midnight
         */
        private Date getMidnightLastNight() {
                Calendar midnight = (Calendar)getCalendar().clone();
                // reset hour, minutes, seconds and millis
                midnight.set(Calendar.HOUR_OF_DAY, 0);
                midnight.set(Calendar.MINUTE, 0);
                midnight.set(Calendar.SECOND, 0);
                midnight.set(Calendar.MILLISECOND, 0);
                return midnight.getTime();
        }
        
        /**
         * Used by Molad based <em>zmanim</em> to determine if <em>zmanim</em> occur during the current day.
         * @see #getMoladBasedTime(Date, Date, Date, boolean)
         * @return following midnight
         */
        private Date getMidnightTonight() {
                Calendar midnight = (Calendar)getCalendar().clone();
                midnight.add(Calendar.DAY_OF_YEAR, 1);//roll to tonight
                midnight.set(Calendar.HOUR_OF_DAY, 0);
                midnight.set(Calendar.MINUTE, 0);
                midnight.set(Calendar.SECOND, 0);
                midnight.set(Calendar.MILLISECOND, 0);
                return midnight.getTime();
        }

        /**
         * Returns the earliest time of <em>Kiddush Levana</em> according to the opinions that it should not be said until 7
         * days after the <em>molad</em>. If the time of <em>tchilas zman Kiddush Levana</em> occurs during the day (between
         * {@link ZmanimCalendar#getAlos72() <em>alos</em>} and {@link ZmanimCalendar#getTzais72() <em>tzais</em>}) it
         * return the next <em>tzais</em>.
         * 
         * @param alos
         *            the beginning of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em>
         *            and ending at <em>tzais</em>), the time returned will be <em>tzais</em>. If either the <em>alos</em> or
         *            <em>tzais</em> parameters are null, no daytime adjustment will be made.
         * @param tzais
         *            the end of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and
         *            ending at <em>tzais</em>), the time returned will be <em>tzais</em>. If either the <em>alos</em> or
         *            <em>tzais</em> parameters are null, no daytime adjustment will be made.
         *
         * @return the Date representing the moment 7 days after the molad. If the time occurs between <em>alos</em> and
         *         <em>tzais</em>, <em>tzais</em> will be returned. If the <em>zman</em> will not occur on this day, a
         *         <code>null</code> will be returned.
         * @see #getTchilasZmanKidushLevana3Days(Date, Date)
         * @see #getTchilasZmanKidushLevana7Days()
         * @see JewishCalendar#getTchilasZmanKidushLevana7Days()
         */
        public Date getTchilasZmanKidushLevana7Days(Date alos, Date tzais) {
                JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                
                // Optimize to not calculate for impossible dates, but account for extreme cases. Tchilas zman kiddush Levana 7 days for
                // the extreme case of Rapa Iti in French Polynesia on Jan 2028 (when kiddush Levana 3 days can be said on the evening
                // of the 30th, the second night of Rosh Chodesh), the 7th day after the molad will be on the 4th of the month.
                // In the case of Anadyr, Russia on Jan, 2071, when sof zman kiddush levana is on the 17th of the month, the 7th day
                // from the molad will be on the 9th day of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
                if (jewishCalendar.getJewishDayOfMonth() < 4 || jewishCalendar.getJewishDayOfMonth() > 9) { 
                        return null;
                }
                
                return getMoladBasedTime(jewishCalendar.getTchilasZmanKidushLevana7Days(), alos, tzais, true);
        }

        /**
         * Returns the earliest time of <em>Kiddush Levana</em> according to the opinions that it should not be said until 7
         * days after the <em>molad</em>. The time will be returned even if it occurs during the day when <em>Kiddush Levana</em>
         * can't be recited. Use {@link #getTchilasZmanKidushLevana7Days(Date, Date)} if you want to limit the time to night hours.
         * 
         * @return the Date representing the moment 7 days after the molad regardless of it is day or night. If the <em>zman</em>
         *         will not occur on this day, a <code>null</code> will be returned.
         * @see #getTchilasZmanKidushLevana7Days(Date, Date)
         * @see JewishCalendar#getTchilasZmanKidushLevana7Days()
         * @see #getTchilasZmanKidushLevana3Days()
         */
        public Date getTchilasZmanKidushLevana7Days() {
                return getTchilasZmanKidushLevana7Days(null, null);
        }

        /**
         * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to
         * the opinion of the<a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a>. This time is identical to the {@link
         * #getSofZmanTfilaGRA() <em>Sof zman tfilah</em> GRA} and is provided as a convenience method for those who are
         * unaware how this <em>zman</em> is calculated. This time is 4 hours into the day based on the opinion of the
         * <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day is calculated from sunrise to sunset.
         * This returns the time 4 * {@link #getShaahZmanisGra()} after {@link #getSeaLevelSunrise() sea level sunrise}. If it
         * is not <em>erev Pesach</em>, a null will be returned.
         * 
         * @see ZmanimCalendar#getShaahZmanisGra()
         * @see ZmanimCalendar#getSofZmanTfilaGRA()
         * @return the <code>Date</code> one is allowed eating <em>chametz</em> on <em>Erev Pesach</em>. If it is not <em>erev
         *         Pesach</em> or the calculation can't be computed such as in the Arctic Circle where there is at least one
         *         day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         */
        public Date getSofZmanAchilasChametzGRA() {
                /*JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) { 
                        return getSofZmanTfilaGRA();
                } else {
                        return null;
                }*/
                return getSofZmanTfilaGRA();
        }

        /**
         * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos72() 72} minutes before {@link #getSunrise() sunrise}. This time is identical to the
         * {@link #getSofZmanTfilaMGA72Minutes() <em>Sof zman tfilah</em> MGA 72 minutes}. This time is 4 {@link #getShaahZmanisMGA()
         * <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72() dawn} based on the opinion of the MGA that the day is
         * calculated from a {@link #getAlos72() dawn} of 72 minutes before sunrise to {@link #getTzais72() nightfall} of 72 minutes
         * after sunset. This returns the time of 4 * {@link #getShaahZmanisMGA()} after {@link #getAlos72() dawn}. If it is not
         * <em>erev Pesach</em>, a null will be returned.
         * 
         * @return the <code>Date</code> of the latest time of eating <em>chametz</em>. If it is not <em>erev Pesach</em> or the
         *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does
         *         not rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of
         *         the {@link AstronomicalCalendar} documentation.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @see #getShaahZmanisMGA()
         * @see #getAlos72()
         * @see #getSofZmanTfilaMGA72Minutes()
         */
        public Date getSofZmanAchilasChametzMGA72Minutes() {
                /*JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getSofZmanTfilaMGA72Minutes();
                } else {
                        return null;
                }*/
                return getSofZmanTfilaMGA72Minutes();
        }
        
        /**
         * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos72Zmanis() 72 zmaniyos} minutes before {@link #getSunrise() sunrise}. This time is identical to the
         * {@link #getSofZmanTfilaMGA72MinutesZmanis() <em>Sof zman tfilah</em> MGA 72 minutes zmanis}. This time is 4 {@link #getShaahZmanis72MinutesZmanis()
         * <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72() dawn} based on the opinion of the MGA that the day is
         * calculated from a {@link #getAlos72Zmanis() dawn} of 72 minutes zmanis before sunrise to {@link #getTzais72Zmanis() nightfall} of 72 minutes zmanis
         * after sunset. This returns the time of 4 * {@link #getShaahZmanis72MinutesZmanis()} after {@link #getAlos72Zmanis() dawn}. If it is not
         * <em>erev Pesach</em>, a null will be returned.
         *
         * @return the <code>Date</code> of the latest time of eating <em>chametz</em>. If it is not <em>erev Pesach</em> or the
         *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does
         *         not rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of
         *         the {@link AstronomicalCalendar} documentation.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @see #getShaahZmanis72MinutesZmanis()
         * @see #getAlos72Zmanis()
         * @see #getSofZmanTfilaMGA72MinutesZmanis()
         */
        public Date getSofZmanAchilasChametzMGA72MinutesZmanis() {
                JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getSofZmanTfilaMGA72MinutesZmanis();
                } else {
                        return null;
                }
        }

        /**
         * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to the
         * opinion of the<a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos16Point1Degrees() 16.1&deg;} before {@link #getSunrise() sunrise}. This time is 4 {@link
         * #getShaahZmanis16Point1Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos16Point1Degrees() dawn}
         * based on the opinion of the MGA that the day is calculated from dawn to nightfall with both being 16.1&deg;
         * below sunrise or sunset. This returns the time of 4 {@link #getShaahZmanis16Point1Degrees()} after
         * {@link #getAlos16Point1Degrees() dawn}. If it is not <em>erev Pesach</em>, a null will be returned.
         * 
         * @return the <code>Date</code> of the latest time of eating <em>chametz</em>. If it is not <em>erev Pesach</em> or the
         *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and north
         *         of the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
         *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getAlos16Point1Degrees()
         * @see #getSofZmanTfilaMGA16Point1Degrees()
         */
        public Date getSofZmanAchilasChametzMGA16Point1Degrees() {
                /*JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getSofZmanTfilaMGA16Point1Degrees();
                } else {
                        return null;
                }*/
                return getSofZmanTfilaMGA16Point1Degrees();
        }

        /**
         * FIXME adjust for synchronous
         * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a>. This time is 5 hours into the day based on the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day is calculated from
         * sunrise to sunset. This returns the time 5 * {@link #getShaahZmanisGra()} after {@link #getSeaLevelSunrise() sea
         * level sunrise}. If it is not  <em>erev Pesach</em>, a null will be returned.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @see ZmanimCalendar#getShaahZmanisGra()
         * @return the <code>Date</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>. If it is not
         *         <em>erev Pesach</em> or the calculation can't be computed such as in the Arctic Circle where there is at least
         *         one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getSofZmanBiurChametzGRA() {
                /*JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getTimeOffset(getElevationAdjustedSunrise(), getShaahZmanisGra() * 5);
                } else {
                        return null;
                }*/
                return getTimeOffset(getElevationAdjustedSunrise(), getShaahZmanisGra() * 5);
        }

        /**
         * FIXME adjust for synchronous
         * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion of
         * the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos72() 72} minutes before {@link #getSunrise() sunrise}. This time is 5 {@link
         * #getShaahZmanisMGA() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72() dawn} based on the opinion of
         * the MGA that the day is calculated from a {@link #getAlos72() dawn} of 72 minutes before sunrise to {@link
         * #getTzais72() nightfall} of 72 minutes after sunset. This returns the time of 5 * {@link #getShaahZmanisMGA()} after
         * {@link #getAlos72() dawn}. If it is not  <em>erev Pesach</em>, a null will be returned.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @return the <code>Date</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>. If it is not
         *         <em>erev Pesach</em> or the calculation can't be computed such as in the Arctic Circle where there is at
         *         least one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisMGA()
         * @see #getAlos72()
         */
        public Date getSofZmanBiurChametzMGA72Minutes() {
                /*JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getTimeOffset(getAlos72(), getShaahZmanisMGA() * 5);
                } else {
                        return null;
                }*/
                return getTimeOffset(getAlos72(), getShaahZmanisMGA() * 5);
        }
        
        /**
         * FIXME adjust for synchronous
         * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion of
         * the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos72Zmanis() 72} minutes zmanis before {@link #getSunrise() sunrise}. This time is 5 {@link
         * #getShaahZmanis72MinutesZmanis() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Zmanis() dawn} based on the opinion of
         * the MGA that the day is calculated from a {@link #getAlos72Zmanis() dawn} of 72 minutes zmanis before sunrise to {@link
         * #getTzais72Zmanis() nightfall} of 72 minutes zmanis after sunset. This returns the time of 5 * {@link #getShaahZmanis72MinutesZmanis()} after
         * {@link #getAlos72Zmanis() dawn}. If it is not  <em>erev Pesach</em>, a null will be returned.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @return the <code>Date</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>. If it is not
         *         <em>erev Pesach</em> or the calculation can't be computed such as in the Arctic Circle where there is at
         *         least one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72MinutesZmanis()
         * @see #getAlos72Zmanis()
         */
        public Date getSofZmanBiurChametzMGA72MinutesZmanis() {
                JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getTimeOffset(getAlos72Zmanis(), getShaahZmanis72MinutesZmanis() * 5);
                } else {
                        return null;
                }
        }

        /**
         * FIXME adjust for synchronous
         * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion
         * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos16Point1Degrees() 16.1&deg;} before {@link #getSunrise() sunrise}. This time is 5
         * {@link #getShaahZmanis16Point1Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos16Point1Degrees()
         * dawn} based on the opinion of the MGA that the day is calculated from dawn to nightfall with both being 16.1&deg;
         * below sunrise or sunset. This returns the time of 5 {@link #getShaahZmanis16Point1Degrees()} after
         * {@link #getAlos16Point1Degrees() dawn}. If it is not  <em>erev Pesach</em>, a null will be returned.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @return the <code>Date</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>. If it is not
         *         <em>erev Pesach</em> or the calculation can't be computed such as northern and southern locations even south
         *         of the Arctic Circle and north of the Antarctic Circle where the sun may not reach low enough below the
         *         horizon for this calculation, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getAlos16Point1Degrees()
         */
        public Date getSofZmanBiurChametzMGA16Point1Degrees() {
                /*JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getTimeOffset(getAlos16Point1Degrees(), getShaahZmanis16Point1Degrees() * 5);
                } else {
                        return null;
                }*/
                return getTimeOffset(getAlos16Point1Degrees(), getShaahZmanis16Point1Degrees() * 5);
        }

        /**
         * A method that returns the <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>'s
         * <em>netz amiti</em> (sunrise) without {@link AstronomicalCalculator#getElevationAdjustment(double)
         * elevation adjustment}. This forms the base for the Baal Hatanya's dawn-based calculations that are
         * calculated as a dip below the horizon before sunrise.
         *
         * According to the Baal Hatanya, <em>netz amiti</em>, or true (halachic) sunrise, is when the top of the sun's
         * disk is visible at an elevation similar to the mountains of Eretz Yisrael. The time is calculated as the point at which
         * the center of the sun's disk is 1.583&deg; below the horizon. This degree-based calculation can be found in Rabbi Shalom
         * DovBer Levine's commentary on The <a href="https://www.chabadlibrary.org/books/pdf/Seder-Hachnosas-Shabbos.pdf">Baal
         * Hatanya's Seder Hachnasas Shabbos</a>. From an elevation of 546 meters, the top of <a href=
         * "https://en.wikipedia.org/wiki/Mount_Carmel">Har Hacarmel</a>, the sun disappears when it is 1&deg; 35' or 1.583&deg;
         * below the sea level horizon. This in turn is based on the Gemara <a href=
         * "https://hebrewbooks.org/shas.aspx?mesechta=2&daf=35">Shabbos 35a</a>. There are other opinions brought down by
         * Rabbi Levine, including Rabbi Yosef Yitzchok Feigelstock who calculates it as the degrees below the horizon 4 minutes after
         * sunset in Yerushalayim (on the equinox). That is brought down as 1.583&deg;. This is identical to the 1&deg; 35' <em>zman</em>
         * and is probably a typo and should be 1.683&deg;. These calculations are used by most <a href=
         * "https://en.wikipedia.org/wiki/Chabad">Chabad</a> calendars that use the Baal Hatanya's <em>zmanim</em>. See
         * <a href="https://www.chabad.org/library/article_cdo/aid/3209349/jewish/About-Our-Zmanim-Calculations.htm">About Our
         * <em>Zmanim</em> Calculations @ Chabad.org</a>.
         *
         * Note: <em>netz amiti</em> is used only for calculating certain <em>zmanim</em>, and is intentionally unpublished. For
         * practical purposes, daytime <em>mitzvos</em> like <em>shofar</em> and <em>lulav</em> should not be done until after the
         * published time for <em>netz</em> / sunrise.
         * 
         * @return the <code>Date</code> representing the exact sea level <em>netz amiti</em> (sunrise) time. If the calculation can't be
         *         computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
         *         where it does not set, a <code>null</code> will be returned. See detailed explanation on top of the page.
         * 
         * @see #getSunrise()
         * @see #getSeaLevelSunrise()
         * @see #getSunsetBaalHatanya()
         * @see #ZENITH_1_POINT_583
         */
        private Date getSunriseBaalHatanya() {
                return getSunriseOffsetByDegrees(ZENITH_1_POINT_583);
        }

        /**
         * A method that returns the <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>'s
         * <em>shkiah amiti</em> (sunset) without {@link AstronomicalCalculator#getElevationAdjustment(double)
         * elevation adjustment}. This forms the base for the Baal Hatanya's dusk-based calculations that are calculated
         * as a dip below the horizon after sunset.
         * 
         * According to the Baal Hatanya, <em>shkiah amiti</em>, true (<em>halachic</em>) sunset, is when the top of the 
         * sun's disk disappears from view at an elevation similar to the mountains of <em>Eretz Yisrael</em>.
         * This time is calculated as the point at which the center of the sun's disk is 1.583 degrees below the horizon.
         *
         * Note: <em>shkiah amiti</em> is used only for calculating certain <em>zmanim</em>, and is intentionally unpublished. For
         * practical purposes, all daytime mitzvos should be completed before the published time for <em>shkiah</em> / sunset.
         *
         * For further explanation of the calculations used for the Baal Hatanya's <em>zmanim</em> in this library, see
         * <a href="https://www.chabad.org/library/article_cdo/aid/3209349/jewish/About-Our-Zmanim-Calculations.htm">About Our
         * <em>Zmanim</em> Calculations @ Chabad.org</a>.
         * 
         * @return the <code>Date</code> representing the exact sea level <em>shkiah amiti</em> (sunset) time. If the calculation
         *         can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not
         *         rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of
         *         the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getSunset()
         * @see #getSeaLevelSunset()
         * @see #getSunriseBaalHatanya()
         * @see #ZENITH_1_POINT_583
         */
        private Date getSunsetBaalHatanya() {
                return getSunsetOffsetByDegrees(ZENITH_1_POINT_583);
        }

        /**
         * A method that returns the <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>'s
         * a <em>shaah zmanis</em> ({@link #getTemporalHour(Date, Date) temporal hour}). This forms the base for the
         * Baal Hatanya's  day  based calculations that are calculated as a 1.583&deg; dip below the horizon after sunset.
         * According to the Baal Hatanya, <em>shkiah amiti</em>, true (halachic) sunset, is when the top of the 
         * sun's disk disappears from view at an elevation similar to the mountains of Eretz Yisrael.
         * This time is calculated as the point at which the center of the sun's disk is 1.583 degrees below the horizon.
         * A method that returns a <em>shaah zmanis</em> ({@link #getTemporalHour(Date, Date) temporal hour}) calculated 
         * based on the <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>'s <em>netz
         * amiti</em> and <em>shkiah amiti</em> using a dip of 1.583&deg; below the sea level horizon. This calculation divides
         * the day based on the opinion of the Baal Hatanya that the day runs from {@link #getSunriseBaalHatanya() netz amiti}
         * to {@link #getSunsetBaalHatanya() <em>shkiah amiti</em>}. The calculations are based on a day from {@link
         * #getSunriseBaalHatanya() sea level <em>netz amiti</em>} to {@link #getSunsetBaalHatanya() sea level <em>shkiah amiti</em>}.
         * The day is split into 12 equal parts with each one being a <em>shaah zmanis</em>. This method is similar to {@link
         * #getTemporalHour}, but all calculations are based on a sea level sunrise and sunset.
         * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em> calculated from
         *         {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)} to {@link #getSunsetBaalHatanya() <em>shkiah amiti</em>
         *         ("real" sunset)}. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a
         *         year where the sun does not rise, and one where it does not set, {@link Long#MIN_VALUE} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getTemporalHour(Date, Date)
         * @see #getSunriseBaalHatanya()
         * @see #getSunsetBaalHatanya()
         * @see #ZENITH_1_POINT_583
         */
        public long getShaahZmanisBaalHatanya() {
                return getTemporalHour(getSunriseBaalHatanya(), getSunsetBaalHatanya());
        }

        /**
         * Returns the <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>'s <em>alos</em>
         * (dawn) calculated as the time when the sun is 16.9&deg; below the eastern {@link #GEOMETRIC_ZENITH geometric horizon}
         * before {@link #getSunrise() sunrise}. For more information the source of 16.9&deg; see {@link #ZENITH_16_POINT_9}.
         * 
         * @see #ZENITH_16_POINT_9
         * @return The <code>Date</code> of dawn. If the calculation can't be computed such as northern and southern
         *         locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not reach
         *         low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getAlosBaalHatanya() {
                return getSunriseOffsetByDegrees(ZENITH_16_POINT_9);
        }

        /**
         * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning). This time is 3
         * {@link #getShaahZmanisBaalHatanya() <em>shaos zmaniyos</em>} (solar hours) after {@link #getSunriseBaalHatanya() 
         * <em>netz amiti</em> (sunrise)} based on the opinion of the Baal Hatanya that the day is calculated from
         * sunrise to sunset. This returns the time 3 * {@link #getShaahZmanisBaalHatanya()} after {@link #getSunriseBaalHatanya() 
         * <em>netz amiti</em> (sunrise)}.
         * 
         * @see ZmanimCalendar#getSofZmanShma(Date, Date)
         * @see #getShaahZmanisBaalHatanya()
         * @return the <code>Date</code> of the latest <em>zman shema</em> according to the Baal Hatanya. If the calculation
         *         can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does
         *         not rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on
         *         top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getSofZmanShmaBaalHatanya() {
                return getSofZmanShma(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * This method returns the latest <em>zman tfilah</em> (time to recite the morning prayers). This time is 4
         * hours into the day based on the opinion of the Baal Hatanya that the day is
         * calculated from sunrise to sunset. This returns the time 4 * {@link #getShaahZmanisBaalHatanya()} after
         * {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}.
         * 
         * @see ZmanimCalendar#getSofZmanTfila(Date, Date)
         * @see #getShaahZmanisBaalHatanya()
         * @return the <code>Date</code> of the latest <em>zman tfilah</em>. If the calculation can't be computed such as in
         *         the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
         *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getSofZmanTfilaBaalHatanya() {
                return getSofZmanTfila(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to the
         * opinion of the Baal Hatanya. This time is identical to the {@link #getSofZmanTfilaBaalHatanya() <em>Sof zman
         * tfilah</em> Baal Hatanya}. This time is 4 hours into the day based on the opinion of the Baal Hatanya that the day
         * is calculated from sunrise to sunset. This returns the time 4 {@link #getShaahZmanisBaalHatanya()} after
         * {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}. If it is not  <em>erev Pesach</em>, a null will be
         * returned.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @see #getShaahZmanisBaalHatanya()
         * @see #getSofZmanTfilaBaalHatanya()
         * @return the <code>Date</code> one is allowed eating <em>chametz</em> on <em>Erev Pesach</em>. If it is not <em>erev
         *         Pesach</em> or the  calculation can't be computed such as in the Arctic Circle where there is at least one
         *         day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getSofZmanAchilasChametzBaalHatanya() {
                /*JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getSofZmanTfilaBaalHatanya();
                } else {
                        return null;
                }*/
                return getSofZmanTfilaBaalHatanya();
        }

        /**
         * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion of
         * the Baal Hatanya. This time is 5 hours into the day based on the opinion of the Baal Hatanya that the day is calculated
         * from sunrise to sunset. This returns the time 5 * {@link #getShaahZmanisBaalHatanya()} after
         * {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}. If it is not  <em>erev Pesach</em>, a null will be returned.
         * @todo in v 3.0.0 enable the calendar check for erev pesach and return <code>null</code> in all other cases.
         * @see #getShaahZmanisBaalHatanya()
         * @return the <code>Date</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>.  If it is not
         *         <em>erev Pesach</em> or the  calculation can't be computed such as in the Arctic Circle where there is at
         *         least one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getSofZmanBiurChametzBaalHatanya() {
                /*JewishCalendar jewishCalendar = new JewishCalendar();
                jewishCalendar.setGregorianDate(getCalendar().get(Calendar.YEAR), getCalendar().get(Calendar.MONTH),
                                getCalendar().get(Calendar.DAY_OF_MONTH));
                if (jewishCalendar.getJewishMonth() == JewishCalendar.NISSAN && jewishCalendar.getJewishDayOfMonth() == 14) {
                        return getTimeOffset(getSunriseBaalHatanya(), getShaahZmanisBaalHatanya() * 5);
                } else {
                        return null;
                }*/
                return getTimeOffset(getSunriseBaalHatanya(), getShaahZmanisBaalHatanya() * 5);
        }

        /**
         * This method returns the time of <em>mincha gedola</em>. <em>Mincha gedola</em> is the earliest time one can pray
         * <em>mincha</em>. The <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> is of the opinion that it is
         * better to delay <em>mincha</em> until {@link #getMinchaKetanaBaalHatanya() <em>mincha ketana</em>} while the
         * <a href="https://en.wikipedia.org/wiki/Asher_ben_Jehiel">Ra"sh</a>,
         * <a href="https://en.wikipedia.org/wiki/Jacob_ben_Asher">Tur</a>, <a href=
         * "https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> and others are of the opinion that <em>mincha</em> can be prayed
         * <em>lechatchila</em> starting at <em>mincha gedola</em>. This is calculated as 6.5 {@link #getShaahZmanisBaalHatanya()
         * sea level solar hours} after {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}. This calculation is based
         * on the opinion of the Baal Hatanya that the day is calculated from sunrise to sunset. This returns the time 6.5
         * * {@link #getShaahZmanisBaalHatanya()} after {@link #getSunriseBaalHatanya() <em>netz amiti</em> ("real" sunrise)}.
         * @todo Consider adjusting this to calculate the time as 30 clock or <em>zmaniyos </em> minutes after either {@link
         *         #getSunTransit() astronomical <em>chatzos</em>} or {@link #getChatzosAsHalfDay() <em>chatzos</em> as half a day}
         *         for {@link AstronomicalCalculator calculators} that support it, based on {@link #isUseAstronomicalChatzos()}.
         * @see #getMinchaGedola(Date, Date)
         * @see #getShaahZmanisBaalHatanya()
         * @see #getMinchaKetanaBaalHatanya()
         * @return the <code>Date</code> of the time of <em>mincha gedola</em> according to the Baal Hatanya. If the calculation
         *         can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise,
         *         and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaGedolaBaalHatanya() {
                return getMinchaGedola(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * FIXME synchronous
         * This is a convenience method that returns the later of {@link #getMinchaGedolaBaalHatanya()} and
         * {@link #getMinchaGedola30Minutes()}. In the winter when 1/2 of a {@link #getShaahZmanisBaalHatanya()
         * <em>shaah zmanis</em>} is less than 30 minutes {@link #getMinchaGedola30Minutes()} will be returned, otherwise
         * {@link #getMinchaGedolaBaalHatanya()} will be returned.
         * @todo Consider adjusting this to calculate the time as 30 clock or <em>zmaniyos </em> minutes after either {@link
         *         #getSunTransit() astronomical <em>chatzos</em>} or {@link #getChatzosAsHalfDay() <em>chatzos</em> as half a day}
         *         for {@link AstronomicalCalculator calculators} that support it, based on {@link #isUseAstronomicalChatzos()}.
         * @return the <code>Date</code> of the later of {@link #getMinchaGedolaBaalHatanya()} and {@link #getMinchaGedola30Minutes()}.
         *         If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year
         *         where the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaGedolaBaalHatanyaGreaterThan30() {
                if (getMinchaGedola30Minutes() == null || getMinchaGedolaBaalHatanya() == null) {
                        return null;
                } else {
                        return getMinchaGedola30Minutes().compareTo(getMinchaGedolaBaalHatanya()) > 0 ? getMinchaGedola30Minutes()
                                        : getMinchaGedolaBaalHatanya();
                }
        }

        /**
         * This method returns the time of <em>mincha ketana</em>. This is the preferred earliest time to pray
         * <em>mincha</em> in the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others.
         * For more information on this see the documentation on {@link #getMinchaGedolaBaalHatanya() <em>mincha gedola</em>}.
         * This is calculated as 9.5 {@link #getShaahZmanisBaalHatanya()  sea level solar hours} after {@link #getSunriseBaalHatanya()
         * <em>netz amiti</em> (sunrise)}. This calculation is calculated based on the opinion of the Baal Hatanya that the
         * day is calculated from sunrise to sunset. This returns the time 9.5 * {@link #getShaahZmanisBaalHatanya()} after {@link
         * #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}.
         * 
         * @see #getMinchaKetana(Date, Date)
         * @see #getShaahZmanisBaalHatanya()
         * @see #getMinchaGedolaBaalHatanya()
         * @return the <code>Date</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getMinchaKetanaBaalHatanya() {
                return getMinchaKetana(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * This method returns the time of <em>plag hamincha</em>. This is calculated as 10.75 hours after sunrise. This
         * calculation is based on the opinion of the Baal Hatanya that the day is calculated
         * from sunrise to sunset. This returns the time 10.75 * {@link #getShaahZmanisBaalHatanya()} after
         * {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}.
         * 
         * @see #getPlagHamincha(Date, Date)
         * @return the <code>Date</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Date getPlagHaminchaBaalHatanya() {
                return getPlagHamincha(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * A method that returns <em>tzais</em> (nightfall) when the sun is 6&deg; below the western geometric horizon
         * (90&deg;) after {@link #getSunset() sunset}. For information on the source of this calculation see
         * {@link #ZENITH_6_DEGREES}.
         * 
         * @return The <code>Date</code> of nightfall. If the calculation can't be computed such as northern and southern
         *         locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not reach
         *         low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_6_DEGREES
         */
        public Date getTzaisBaalHatanya() {
                return getSunsetOffsetByDegrees(ZENITH_6_DEGREES);
        }
        
        /**
         * A utility method to calculate zmanim based on <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe
         * Feinstein</a> as calculated in <a href="https://en.wikipedia.org/wiki/Mesivtha_Tifereth_Jerusalem">MTJ</a>, <a href=
         * "https://en.wikipedia.org/wiki/Mesivtha_Tifereth_Jerusalem">Yeshiva of Staten Island</a>, and Camp Yeshiva
         * of Staten Island. The day is split in two, from <em>alos</em> / sunrise to fixed local <em>chatzos</em>, and the
         * second half of the day, from fixed local <em>chatzos</em> to sunset / <em>tzais</em>. Morning based times are calculated
         * based on the first 6 hours, and afternoon times based on the second half of the day.
         * @deprecated This method will be replaced in v3.0.0 by the more generic {@link
         *         ZmanimCalendar#getHalfDayBasedZman(Date, Date, double)} method.
         * 
         * @param startOfHalfDay
         *            The start of the half day. This would be <em>alos</em> or sunrise for morning based times and fixed
         *            local <em>chatzos</em> for the second half of the day.
         * @param endOfHalfDay
         *            The end of the half day. This would be fixed local <em>chatzos</em> for morning based times and sunset
         *            or <em>tzais</em> for afternoon based times.
         * @param hours
         *            the number of hours to offset the beginning of the first or second half of the day
         * 
         * @return the <code>Date</code> of the <em>zman</em> based on calculation of the first or second half of the day. If
         *         the calculation can't be computed such as in the Arctic Circle where there is at least one day a year where
         *         the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         *
         * @see ComplexZmanimCalendar#getFixedLocalChatzos()
         * @see ZmanimCalendar#getHalfDayBasedZman(Date, Date, double)
         */
        @Deprecated // (forRemoval=true) // add back once Java 9 is the minimum supported version
        public Date getFixedLocalChatzosBasedZmanim(Date startOfHalfDay, Date endOfHalfDay, double hours) {
                return getHalfDayBasedZman(startOfHalfDay, endOfHalfDay, hours);
        }
        
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
         * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> that the
         * day is calculated from dawn to nightfall, but calculated using the first half of the day only. The half a day starts
         * at <em>alos</em> defined as {@link #getAlos18Degrees() 18&deg;} and ends at {@link #getFixedLocalChatzos() fixed local
         * chatzos}. <em>Sof Zman Shema</em> is 3 <em>shaos zmaniyos</em> (solar hours) after <em>alos</em> or half of this half-day.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos18Degrees()
         * @see #getFixedLocalChatzos()
         * @see ZmanimCalendar#getHalfDayBasedZman(Date, Date, double)
         */
        public Date getSofZmanShmaMGA18DegreesToFixedLocalChatzos() {
                return getHalfDayBasedZman(getAlos18Degrees(), getFixedLocalChatzos(), 3);
        }
        
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
         * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> that the
         * day is calculated from dawn to nightfall, but calculated using the first half of the day only. The half a day starts
         * at <em>alos</em> defined as {@link #getAlos16Point1Degrees() 16.1&deg;} and ends at {@link #getFixedLocalChatzos() fixed local
         * chatzos}. <em>Sof Zman Shema</em> is 3 <em>shaos zmaniyos</em> (solar hours) after this <em>alos</em> or half of this half-day.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos16Point1Degrees()
         * @see #getFixedLocalChatzos()
         * @see #getHalfDayBasedZman(Date, Date, double)
         */
        public Date getSofZmanShmaMGA16Point1DegreesToFixedLocalChatzos() {
                return getHalfDayBasedZman(getAlos16Point1Degrees(), getFixedLocalChatzos(), 3);
        }
        
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
         * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> that the
         * day is calculated from dawn to nightfall, but calculated using the first half of the day only. The half a day starts
         * at <em>alos</em> defined as {@link #getAlos90() 90 minutes before sunrise} and ends at {@link #getFixedLocalChatzos()
         * fixed local chatzos}. <em>Sof Zman Shema</em> is 3 <em>shaos zmaniyos</em> (solar hours) after this <em>alos</em> or
         * half of this half-day.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos90()
         * @see #getFixedLocalChatzos()
         * @see #getHalfDayBasedZman(Date, Date, double)
         */
        public Date getSofZmanShmaMGA90MinutesToFixedLocalChatzos() {
                return getHalfDayBasedZman(getAlos90(), getFixedLocalChatzos(), 3);
        }
        
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
         * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombinern">Magen Avraham (MGA)</a> that the
         * day is calculated from dawn to nightfall, but calculated using the first half of the day only. The half a day starts
         * at <em>alos</em> defined as {@link #getAlos72() 72 minutes before sunrise} and ends at {@link #getFixedLocalChatzos()
         * fixed local chatzos}. <em>Sof Zman Shema</em> is 3 <em>shaos zmaniyos</em> (solar hours) after this <em>alos</em> or
         * half of this half-day.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos72()
         * @see #getFixedLocalChatzos()
         * @see #getHalfDayBasedZman(Date, Date, double)
         */
        public Date getSofZmanShmaMGA72MinutesToFixedLocalChatzos() {
                return getHalfDayBasedZman(getAlos72(), getFixedLocalChatzos(), 3);
        }
                
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
         * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
         * opinion of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day is calculated from
         * sunrise to sunset, but calculated using the first half of the day only. The half a day starts at {@link #getSunrise()
         * sunrise} and ends at {@link #getFixedLocalChatzos() fixed local chatzos}. <em>Sof zman Shema</em> is 3 <em>shaos
         * zmaniyos</em> (solar hours) after sunrise or half of this half-day.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getSunrise()
         * @see #getFixedLocalChatzos()
         * @see #getHalfDayBasedZman(Date, Date, double)
         */
        public Date getSofZmanShmaGRASunriseToFixedLocalChatzos() {
                return getHalfDayBasedZman(getSunrise(), getFixedLocalChatzos(), 3);
        }
        
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
         * calculation of <em>sof zman tfila</em> (<em>zman tfilah</em> (the latest time to recite the morning prayers))
         * according to the opinion of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day is
         * calculated from sunrise to sunset, but calculated using the first half of the day only. The half a day starts at
         * {@link #getSunrise() sunrise} and ends at {@link #getFixedLocalChatzos() fixed local chatzos}. <em>Sof zman tefila</em>
         * is 4 <em>shaos zmaniyos</em> (solar hours) after sunrise or 2/3 of this half-day.
         * 
         * @return the <code>Date</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getSunrise()
         * @see #getFixedLocalChatzos()
         * @see #getHalfDayBasedZman(Date, Date, double)
         */
        public Date getSofZmanTfilaGRASunriseToFixedLocalChatzos() {
                return getHalfDayBasedZman(getSunrise(), getFixedLocalChatzos(), 4);
        }
        
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of
         * the calculation of <em>mincha gedola</em>, the earliest time one can pray <em>mincha</em> <a href=
         * "https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a>that is 30 minutes after {@link #getFixedLocalChatzos() fixed
         * local chatzos}.
         * 
         * @return the <code>Date</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         * @see #getMinchaGedola()
         * @see #getFixedLocalChatzos()
         * @see #getMinchaKetanaGRAFixedLocalChatzosToSunset
         */
        public Date getMinchaGedolaGRAFixedLocalChatzos30Minutes() {
                return getTimeOffset(getFixedLocalChatzos(), MINUTE_MILLIS * 30);
        }
        
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion
         * of the calculation of <em>mincha ketana</em> (the preferred time to recite the <em>mincha prayers</em> according to
         * the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others) calculated according
         * to the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that is 3.5 <em>shaos zmaniyos</em> (solar
         * hours) after {@link #getFixedLocalChatzos() fixed local chatzos}.
         * 
         * @return the <code>Date</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         *         
         * @see #getMinchaGedola()
         * @see #getFixedLocalChatzos()
         * @see #getMinchaGedolaGRAFixedLocalChatzos30Minutes
         * @see ZmanimCalendar#getHalfDayBasedZman(Date, Date, double)
         */
        public Date getMinchaKetanaGRAFixedLocalChatzosToSunset() {
                return getHalfDayBasedZman(getFixedLocalChatzos(), getSunset(), 3.5);
        }
        
        /**
         * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion
         * of the calculation of <em>plag hamincha</em>. This method returns <em>plag hamincha</em> calculated according to the
         * <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day ends at sunset and is 4.75 <em>shaos
         * zmaniyos</em> (solar hours) after {@link #getFixedLocalChatzos() fixed local chatzos}.
         * 
         * @return the <code>Date</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
         *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
         *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         *         
         * @see #getPlagHamincha()
         * @see #getFixedLocalChatzos()
         * @see #getMinchaKetanaGRAFixedLocalChatzosToSunset
         * @see #getMinchaGedolaGRAFixedLocalChatzos30Minutes
         * @see ZmanimCalendar#getHalfDayBasedZman(Date, Date, double)
         */
        public Date getPlagHaminchaGRAFixedLocalChatzosToSunset() {
                return getHalfDayBasedZman(getFixedLocalChatzos(), getSunset(), 4.75);
        }
        
        /**
         * Method to return <em>tzais</em> (dusk) calculated as 50 minutes after sea level sunset. This method returns
         * <em>tzais</em> (nightfall) based on the opinion of Rabbi Moshe Feinstein for the New York area. This time should
         * not be used for latitudes other than ones similar to the latitude of the NY area.
         * 
         * @return the <code>Date</code> representing the time. If the calculation can't be computed such as in the Arctic
         *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
         *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         */
        public Date getTzais50() {
                return getTimeOffset(getElevationAdjustedSunset(), 50 * MINUTE_MILLIS);
        }
        
        /**
         * A method for calculating <em>samuch lemincha ketana</em>, / near <em>mincha ketana</em> time that is half an hour before
         * {@link #getMinchaKetana()} or is 9 * {@link #getShaahZmanisGra() <em>shaos zmaniyos</em>} (solar hours) after {@link
         * #getSunrise() sunrise} or {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link #isUseElevation()}
         * setting), calculated according to the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> using a day starting at
         * sunrise and ending at sunset. This is the time that eating or other activity can't begin prior to praying <em>mincha</em>.
         * The calculation used is 9 * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() <em>alos</em>
         * 16.1&deg;}. See the <a href="https://hebrewbooks.org/pdfpager.aspx?req=60387&st=&pgnum=294">Mechaber and Mishna Berurah
         * 232</a> and <a href="https://hebrewbooks.org/pdfpager.aspx?req=60388&pgnum=34">249:2</a>.
         * 
         * @see #getShaahZmanisGra()
         * @see #getSamuchLeMinchaKetana16Point1Degrees()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         * @return the <code>Date</code> of the time of <em>samuch lemincha ketana</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getSamuchLeMinchaKetanaGRA() {
                return getSamuchLeMinchaKetana(getElevationAdjustedSunrise(), getElevationAdjustedSunset(), true);
        }
        
        /**
         * A method for calculating <em>samuch lemincha ketana</em>, / near <em>mincha ketana</em> time that is half an hour
         * before {@link #getMinchaGedola16Point1Degrees()}  or 9 * <em>shaos zmaniyos</em> (temporal hours) after the start of
         * the day, calculated using a day starting and ending 16.1&deg; below the horizon. This is the time that eating or other
         * activity can't begin prior to praying <em>mincha</em>. The calculation used is 9 * {@link
         * #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;}. See the <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=60387&st=&pgnum=294">Mechaber and Mishna Berurah 232</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=60388&pgnum=34">249:2</a>.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         * @return the <code>Date</code> of the time of <em>samuch lemincha ketana</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getSamuchLeMinchaKetana16Point1Degrees() {
                return getSamuchLeMinchaKetana(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
        }
        
        /**
         * A method for calculating <em>samuch lemincha ketana</em>, / near <em>mincha ketana</em> time that is half an hour before
         * {@link #getMinchaKetana72Minutes()}  or 9 * <em>shaos zmaniyos</em> (temporal hours) after the start of the day,
         * calculated using a day starting 72 minutes before sunrise and ending 72 minutes after sunset. This is the time that eating
         * or other activity can't begin prior to praying <em>mincha</em>. The calculation used is 9 * {@link
         * #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() <em>alos</em> 16.1&deg;}. See the <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=60387&st=&pgnum=294">Mechaber and Mishna Berurah 232</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=60388&pgnum=34">249:2</a>.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         * @return the <code>Date</code> of the time of <em>samuch lemincha ketana</em>. If the calculation can't be computed such
         *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
         *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Date getSamuchLeMinchaKetana72Minutes() {
                return getSamuchLeMinchaKetana(getAlos72(), getTzais72(), true);
        }
}