/*
 * Zmanim Java API
 * Copyright © 2004-2026 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; version 2.1 of the License.
 *
 * 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.time.Duration;
import java.time.Instant;
import java.time.LocalTime;
import java.time.temporal.ChronoUnit;

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">Yisroe
 * 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 its 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()} 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:
 * 
 * {@snippet lang='java' :
 * String locationName = "Lakewood, NJ";
 * double latitude = 40.0828; // Lakewood, NJ
 * double longitude = -74.222; // Lakewood, NJ
 * double elevation = 20; // optional elevation correction in Meters
 * // @link region="target_zone_link" substring="getAvailableZoneIds()" target="java.time.ZoneId#getAvailableZoneIds()"
 * ZoneId zoneId = ZoneId.of("America/New_York"); // set the zoneId to a valid ZoneId listed in getAvailableZoneIds()
 * // @end
 * GeoLocation location = new GeoLocation(locationName, latitude, longitude, elevation, zoneId);
 * ComprehensiveZmanimCalendar czc = new ComprehensiveZmanimCalendar(location);
 * // Optionally set the date or it will default to today's date
 * ZonedDateTime dateTime = ZonedDateTime.of(1969, Month.FEBRUARY.getValue(), 8, 0, 0, 0, 0, location.getZoneId());
 * czc.setZonedDateTime(dateTime);
 * }
 * 
 * <b>Note:</b> For locations such as Israel where the beginning and end of daylight savings time used to 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 time zone database</a>, create a
 * {@link java.time.ZoneId} with the known start and end of DST.
 * To get <em>alos</em> calculated as 14° below the horizon (as calculated in the calendars published in Montreal),
 * add {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90) to the 14° offset to get the desired time:
 * {@snippet lang='java' :
 * Instant alos14 = czc.getSunriseOffsetByDegrees(AstronomicalCalendar.GEOMETRIC_ZENITH + 14);
 * }
 * To get <em>mincha gedola</em> calculated based on the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham
 * (MGA)</a> using a <em>shaah zmanis</em> based on the day starting 16.1° below the horizon (and ending 16.1° after sunset) the
 * following calculation can be used:
 * 
 * {@snippet lang='java' :
 * Instant minchaGedola = czc.getTimeOffset(czc.getAlos16point1Degrees(), czc.getShaahZmanis16Point1Degrees() * 6.5);
 * }
 * or even simpler using the included convenience methods
 * {@snippet lang='java' :
 * Instant minchaGedola = czc.getMinchaGedola(czc.getAlos16point1Degrees(), czc.getShaahZmanis16Point1Degrees());
 * }
 * 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° before
 * sunrise and ending at <em>tzais</em> of 7.083° 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.
 * {@snippet lang='java' :
 * Instant plag = czc.getPlagHamincha(czc.getSunriseOffsetByDegrees(AstronomicalCalendar.GEOMETRIC_ZENITH + 12),
 *              czc.getSunsetOffsetByDegrees(AstronomicalCalendar.GEOMETRIC_ZENITH + ZmanimCalendar.ZENITH_7_POINT_083));
 * }
 * 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> {@code Duration} for this day</li>
 *      <li>Add 9 of these <em>shaos zmaniyos</em> to <em>alos</em> starting at 12°</li>
 * </ol>
 * {@snippet lang='java' :
 * Duration shaahZmanis = czc.getTemporalHour(czc.getSunriseOffsetByDegrees(AstronomicalCalendar.GEOMETRIC_ZENITH} + 12),
 *                              czc.getSunsetOffsetByDegrees(AstronomicalCalendar.GEOMETRIC_ZENITH + ZmanimCalendar.ZENITH_7_POINT_083));
 * Instant sofZmanAchila = getTimeOffset(czc.getSunriseOffsetByDegrees(AstronomicalCalendar.GEOMETRIC_ZENITH} + 12),
 *                              shaahZmanis * 9);
 * }
 * Calculating this <em>sof zman achila</em> according to the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a>
 * is simplicity itself.
 * {@snippet lang='java' :
 * Instant sofZmanAchila = czc.getTimeOffset(czc.getSunrise(), czc.getShaahZmanisGRA() * 9);
 * }
 * 
 * <h2>See documentation from the {@link ZmanimCalendar} parent class</h2>
 * 
 * @author © Eliyahu Hershfeld 2004 - 2026
 */
public class ComprehensiveZmanimCalendar extends ZmanimCalendar {

        /**
         * The zenith of 3.7° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim3Point7Degrees()
         */
        protected static final double ZENITH_3_POINT_7 = GEOMETRIC_ZENITH + 3.7;

        /**
         * The zenith of 3.8° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim3Point8Degrees()
         */
        protected static final double ZENITH_3_POINT_8 = GEOMETRIC_ZENITH + 3.8;

        /**
         * The zenith of 5.95° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim5Point95Degrees()
         */
        protected static final double ZENITH_5_POINT_95 = GEOMETRIC_ZENITH + 5.95;

        /**
         * The zenith of 7.083° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). This is often referred to as
         * 7°5' (7° and 5 minutes).
         * 
         * @see #getTzaisGeonim7Point083Degrees()
         * @see #getBainHashmashosRT13Point5MinutesBefore7Point083Degrees()
         */
        protected static final double ZENITH_7_POINT_083 = GEOMETRIC_ZENITH + 7 + (5.0 / 60);

        /**
         * The zenith of 10.2° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getMisheyakir10Point2Degrees()
         */
        protected static final double ZENITH_10_POINT_2 = GEOMETRIC_ZENITH + 10.2;

        /**
         * The zenith of 11° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getMisheyakir11Degrees()
         */
        protected static final double ZENITH_11_DEGREES = GEOMETRIC_ZENITH + 11;

        /**
         * The zenith of 11.5° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getMisheyakir11Point5Degrees()
         */
        protected static final double ZENITH_11_POINT_5 = GEOMETRIC_ZENITH + 11.5;
        
        /**
         * The zenith of 12.85° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getMisheyakir12Point85Degrees()
         */
        protected static final double ZENITH_12_POINT_85 = GEOMETRIC_ZENITH + 12.85;

        /**
         * The zenith of 13.24° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getBainHashmashosRT13Point24Degrees
         */
        protected static final double ZENITH_13_POINT_24 = GEOMETRIC_ZENITH + 13.24;
        
        /**
         * The zenith of 19° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getAlos19Degrees()
         * @see #ZENITH_19_POINT_8
         */
        protected static final double ZENITH_19_DEGREES = GEOMETRIC_ZENITH + 19;

        /**
         * The zenith of 19.8° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzais19Point8Degrees()
         * @see #getAlos19Point8Degrees()
         * @see #ZENITH_19_DEGREES
         */
        protected static final double ZENITH_19_POINT_8 = GEOMETRIC_ZENITH + 19.8;

        /**
         * The zenith of 26° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getAlos26Degrees()
         * @see #getTzais26Degrees()
         * @see #getAlos120Minutes()
         * @see #getTzais120Minutes()
         */
        protected static final double ZENITH_26_DEGREES = GEOMETRIC_ZENITH + 26.0;

        /**
         * The zenith of 4.42° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim4Point42Degrees()
         */
        protected static final double ZENITH_4_POINT_42 = GEOMETRIC_ZENITH + 4.42;

        /**
         * The zenith of 4.66° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim4Point66Degrees()
         */
        protected static final double ZENITH_4_POINT_66 = GEOMETRIC_ZENITH + 4.66;

        /**
         * The zenith of 4.8° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim4Point8Degrees()
         */
        protected static final double ZENITH_4_POINT_8 = GEOMETRIC_ZENITH + 4.8;

        /**
         * The zenith of 16.9° below geometric zenith (90°).
         *
         * @see #getAlosBaalHatanya()
         */
        protected static final double ZENITH_16_POINT_9 = GEOMETRIC_ZENITH + 16.9;

        /**
         * The zenith of 6° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisBaalHatanya()
         */
        protected static final double ZENITH_6_DEGREES = GEOMETRIC_ZENITH + 6;

        /**
         * The zenith of 6.45° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim6Point45Degrees()
         */
        protected static final double ZENITH_6_POINT_45 = GEOMETRIC_ZENITH + 6.45;
        
        /**
         * The zenith of 7.65° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getMisheyakir7Point65Degrees()
         */
        protected static final double ZENITH_7_POINT_65 = GEOMETRIC_ZENITH + 7.65;
        
        /**
         * The zenith of 7.67° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim7Point67Degrees()
         */
        protected static final double ZENITH_7_POINT_67 = GEOMETRIC_ZENITH + 7.67;
        
        /**
         * The zenith of 9.3° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getTzaisGeonim9Point3Degrees()
         */
        protected static final double ZENITH_9_POINT_3 = GEOMETRIC_ZENITH + 9.3;
        
        /**
         * The zenith of 9.5° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°).
         * @see #getMisheyakir9Point5Degrees()
         */
        protected static final double ZENITH_9_POINT_5 = GEOMETRIC_ZENITH + 9.5;
        
        /**
         * The zenith of 9.75° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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° <b>above</b> {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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° less without this.
         * 
         * @see #getBainHashmashosYereim2Point1Degrees()
         */
        protected static final double ZENITH_MINUS_2_POINT_1 = GEOMETRIC_ZENITH - 2.1;
        
        /**
         * The zenith of 2.8° above {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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° less without this.
         * 
         * @see #getBainHashmashosYereim2Point8Degrees()
         */
        protected static final double ZENITH_MINUS_2_POINT_8 = GEOMETRIC_ZENITH - 2.8;
        
        /**
         * The zenith of 3.05° above {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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° 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 ComprehensiveZmanimCalendar(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()
         * @see ComprehensiveZmanimCalendar(GeoLocation)
         */
        public ComprehensiveZmanimCalendar() {
                super();
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a 19.8° dip. This calculation
         * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen
         * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is when the sun is 19.8°
         * below the eastern geometric horizon before sunrise. Dusk for this is when the sun is 19.8° 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 Duration} 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 {@code null} will be returned. See detailed explanation on top
         *         of the {@link AstronomicalCalendar} documentation.
         */
        public Duration getShaahZmanis19Point8Degrees() {
                return getTemporalHour(getAlos19Point8Degrees(), getTzais19Point8Degrees());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a 18° dip. This calculation divides
         * the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham
         * (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is when the sun is 18° below the
         * eastern geometric horizon before sunrise. Dusk for this is when the sun is 18° 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 Duration} 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 {@code null} will be returned. See detailed explanation on top
         *         of the {@link AstronomicalCalendar} documentation.
         */
        public Duration getShaahZmanis18Degrees() {
                return getTemporalHour(getAlos18Degrees(), getTzais18Degrees());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 26°. This calculation divides the day based
         * on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> that the day runs from
         * dawn to dusk. Dawn for this calculation is when the sun is {@link #getAlos26Degrees() 26°} below the eastern geometric horizon
         * before sunrise. Dusk for this is when the sun is {@link #getTzais26Degrees() 26°} 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° 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 Duration} 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 {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis120Minutes()
         */
        public Duration getShaahZmanis26Degrees() {
                return getTemporalHour(getAlos26Degrees(), getTzais26Degrees());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 16.1°. 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° below the eastern
         * geometric horizon before sunrise and dusk is when the sun is 16.1° 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 Duration}  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 {@code null} 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 Duration 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_Gombiner">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 ComprehensiveZmanimCalendar}.
         * 
         * @return the {@code Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos60Minutes()
         * @see #getTzais60Minutes()
         * @see #getPlagHamincha60Minutes()
         */
        public Duration getShaahZmanis60Minutes() {
                return getTemporalHour(getAlos60Minutes(), getTzais60Minutes());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombiner">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()} to {@link #getSunset()}.
         * 
         * @return the {@code Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Zmanis()
         * @see #getTzais72Zmanis()
         */
        public Duration 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_Gombiner">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 Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Duration getShaahZmanis90Minutes() {
                return getTemporalHour(getAlos90Minutes(), getTzais90Minutes());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos90Zmanis() 90} minutes <em>zmaniyos</em> before {@link #getSunrise()}. This calculation divides the day
         * based on the opinion of the MGA that the day runs from dawn to dusk. Dawn is calculated as 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()} to {@link #getSunset() sunset}.
         * 
         * @return the {@code Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos90Zmanis()
         * @see #getTzais90Zmanis()
         */
        public Duration 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link #getAlos96Zmanis()
         * 96} minutes <em>zmaniyos</em> before {@link #getSunrise()}. This calculation divides the day based on the opinion of the
         * MGA that the day runs from dawn to dusk. Dawn is calculated as 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()} to {@link #getSunset() sunset}.
         * 
         * @return the {@code Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos96Zmanis()
         * @see #getTzais96Zmanis()
         */
        public Duration 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()}, 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 Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Zmanis()
         * @see #getTzaisAteretTorah()
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         */
        public Duration 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°} and ending 14 minutes after sunset in degrees {@link
         * #getTzaisGeonim3Point8Degrees() <em>tzais</em> 3.8°}. 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_mile">mil</a>,
         * with half a minute added for Rav Yosi's <em>Bain Hashmashos</em>. Sources for an asymmetrical day-based calculation can be
         * seen in the documentation of {@link #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees}.
         * 
         * @return the {@code Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getMinchaKetanaAhavatShalom()
         * @see #getPlagAhavatShalom()
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point7Degrees()
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim7Point083Degrees()
         */
        public Duration getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point8Degrees() {
                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°} and ending 13.5 minutes after sunset in degrees {@link
         * #getTzaisGeonim3Point7Degrees() <em>tzais</em> 3.7°}. 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.
         * Sources for an asymmetrical day-based calculation can be seen in the documentation of
         * {@link #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees}.
         * 
         * @return the {@code Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getMinchaGedolaAhavatShalom()
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point8Degrees()
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim7Point083Degrees()
         */
        public Duration getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point7Degrees() {
                return getTemporalHour(getAlos16Point1Degrees(), getTzaisGeonim3Point7Degrees());
        }
        
        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) used by some <em>zmanim</em> according to some opinions that is based
         * on a day starting  at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ending {@link
         * #getTzaisGeonim7Point083Degrees <em>tzais</em> 8.083°}. 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}. Sources for an asymmetrical day-based calculation can be seen in the documentation
         * of {@link #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees}.
         * 
         * @return the {@code Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point7Degrees()
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point8Degrees()
         */
        public Duration getShaahZmanisAlos16Point1DegreesToTzaisGeonim7Point083Degrees() {
                return getTemporalHour(getAlos16Point1Degrees(), getTzaisGeonim7Point083Degrees());
        }

        /**
         * 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_Gombiner">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 Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Duration getShaahZmanis96Minutes() {
                return getTemporalHour(getAlos96Minutes(), getTzais96Minutes());
        }

        /**
         * 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_Gombiner">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° 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 Duration} of a <em>shaah zmanis</em>. If the calculation can't be computed such as inin the Arctic
         *         Circle where there is at least one day a year when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis26Degrees()
         */
        public Duration getShaahZmanis120Minutes() {
                return getTemporalHour(getAlos120Minutes(), getTzais120Minutes());
        }

        /**
         * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
         * "https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos120Zmanis() 120} minutes <em>zmaniyos</em> before {@link #getSunrise()}. 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()} 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° 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 Duration} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos120Zmanis()
         * @see #getTzais120Zmanis()
         */
        public Duration 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 Instant} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis120MinutesZmanis()
         * @see #getAlos120Minutes()
         * @see #getTzais120Minutes()
         * @see #getPlagHamincha26Degrees()
         * @see #getPlagHamincha120Minutes()
         */
        @Deprecated (forRemoval=false)
        public Instant getPlagHamincha120MinutesZmanis() {
                return getPlagHamincha(getAlos120Zmanis(), getTzais120Zmanis(), true);
        }

        /**
         * {@summary This method <em>plag hamincha</em> according to the Magen Avraham with the day starting at {@link
         * #getAlos120Minutes()}. It should be used <em>lechumra</em> only}. This is calculated as 10.75 * {@link
         * #getShaahZmanis120Minutes()} after {@link #getAlos120Minutes()}. Since the <em>zman</em> based on an extremely early
         * <em>alos</em> and a very late <em>tzais</em>, it returns a very late time (often after <em>shkiah</em> and can result in
         * <em>chillul Shabbos</em> etc.) and 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 Instant} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis120Minutes()
         * @see #getPlagHamincha26Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant getPlagHamincha120Minutes() {
                return getPlagHamincha(getAlos120Minutes(), getTzais120Minutes(), true);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated as 60 minutes before {@link #getSunriseBasedOnElevationSetting()} (depends on
         * the {@link #isUseElevation()} setting). This is the time to walk the distance of 4 <a href=
         * "https://en.wikipedia.org/wiki/Biblical_mile">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 opinions
         * 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 Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzais60Minutes()
         * @see #getTzaisGeonim9Point75Degrees()
         * @see #getPlagHamincha60Minutes()
         * @see #getShaahZmanis60Minutes()
         */
        public Instant getAlos60Minutes() {
                return getTimeOffset(getSunriseBasedOnElevationSetting(), Duration.ofMinutes(-60));
        }

        /**
         * 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_mile">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()}
         * to {@link #getSeaLevelSunset() sea level sunset} or {@link #getSunrise()} to {@link #getSunset()} (depending on the
         * {@link #isUseElevation()} setting). The actual calculation is {@link #getSunriseBasedOnElevationSetting()} - ({@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 Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will
         *         be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisGRA()
         */
        public Instant getAlos72Zmanis() {
                return getZmanisBasedOffset(-1.2);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated using 96 minutes before {@link #getSunriseBasedOnElevationSetting()}
         * (depends 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_mile">mil</a> at 24 minutes a mil. Time based offset calculations for <em>alos</em>
         * are based on the opinion 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 Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant getAlos96Minutes() {
                return getTimeOffset(getSunriseBasedOnElevationSetting(), Duration.ofMinutes(-96));
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated using 90 minutes <em>zmaniyos</em> or 1/8th of the day before {@link
         * #getSunrise()} or {@link #getSeaLevelSunrise()} (depending on the {@link #isUseElevation()} setting). This is based on a
         * 22.5-minute <a href="https://en.wikipedia.org/wiki/Biblical_mile">mil</a> so the time for 4 mil is 90 minutes which is 1/8th
         * of a day (12 * 60) / 8 = 90. The actual calculation used is {@link #getSunriseBasedOnElevationSetting()} -
         * ({@link #getShaahZmanisGRA()} * 1.5).
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will
         *         be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisGRA()
         */
        public Instant 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
         * #getSunriseBasedOnElevationSetting()} (depends on the {@link #isUseElevation()} setting). This is based on a 24-minute
         * <a href="https://en.wikipedia.org/wiki/Biblical_mile">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 #getSunriseBasedOnElevationSetting()} to to {@link
         * #getSunsetBasedOnElevationSetting()} (depends on the {@link #isUseElevation()}. The actual calculation used is {@link
         *  #getSunriseBasedOnElevationSetting()} - ({@link #getShaahZmanisGRA()} * 1.6).
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisGRA()
         */
        public Instant getAlos96Zmanis() {
                return getZmanisBasedOffset(-1.6);
        }

        /**
         * Method to return <em>alos</em> (dawn) calculated using 90 minutes before {@link #getSunriseBasedOnElevationSetting()}
         * (depends on the {@link #isUseElevation()} setting) based on the time to walk the distance of 4 <a href=
         * "https://en.wikipedia.org/wiki/Biblical_mile">mil</a> at 22.5 minutes a mil. Time-based offset calculations for <em>alos</em>
         * are based on the opinion 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 Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant getAlos90Minutes() {
                return getTimeOffset(getSunriseBasedOnElevationSetting(), Duration.ofMinutes(-90));
        }

        /**
         * This method should be used <em>lechumra</em> only and returns <em>alos</em> (dawn) calculated using 120 minutes before {@link
         * #getSunriseBasedOnElevationSetting()} (that depends on the {@link #isUseElevation()} setting) based on the time to walk the
         * distance of 5 <a href="https://en.wikipedia.org/wiki/Biblical_mile">mil</a> (<em>Ula</em>) at 24 minutes a mil. Time based
         * offset calculations for <em>alos</em> are based on the* opinions 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 Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzais120Minutes()
         * @see #getAlos26Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant getAlos120Minutes() {
                return getTimeOffset(getSunriseBasedOnElevationSetting(), Duration.ofMinutes(-120));
        }

        /**
         * 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 #getSunriseBasedOnElevationSetting()} (depends on the {@link
         * #isUseElevation()} setting). This is based on a 24-minute <a href="https://en.wikipedia.org/wiki/Biblical_mile">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
         * #getSunriseBasedOnElevationSetting()} to {@link #getSunsetBasedOnElevationSetting()} (depends on the {@link #isUseElevation()}.
         * The actual calculation used is {@link #getSunset()} - ({@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 Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos120Minutes()
         * @see #getAlos26Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant 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°} below the eastern geometric horizon before sunrise. This calculation is based on the same
         * calculation of {@link #getAlos120Minutes() 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° below {@link AstronomicalCalendar#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 Instant} 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} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos120Minutes()
         * @see #getTzais120Minutes()
         * @see #getTzais26Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant getAlos26Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_26_DEGREES);
        }

        /**
         * A method to return <em>alos</em> (dawn) calculated when the sun is {@link ASTRONOMICAL_ZENITH 18°} below the
         * eastern geometric horizon before sunrise.
         * 
         * @return the {@code Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see ASTRONOMICAL_ZENITH
         */
        public Instant getAlos18Degrees() {
                return getSunriseOffsetByDegrees(ASTRONOMICAL_ZENITH);
        }
        
        /**
         * A method to return <em>alos</em> (dawn) calculated when the sun is {@link #ZENITH_19_DEGREES 19°} 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 Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant 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°} below the
         * eastern geometric horizon before sunrise. This calculation is based on the same calculation of
         * {@link #getAlos90Minutes() 90 minutes} before sunrise, 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° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH}.
         * 
         * @return the {@code Instant} 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} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos90Minutes()
         * @see #getTzais19Point8Degrees()
         */
        public Instant getAlos19Point8Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_19_POINT_8);
        }
        
        /**
         * This method returns <em>misheyakir</em> based on the position of the sun {@link #ZENITH_12_POINT_85 12.85°}
         * below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). This is based on the position of the sun slightly
         * later than 57 minutes before {@link #getSunrise()} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>. This
         * <em>zman</em> is mentioned for use <b><em>bish'as hadchak</em></b> in the Birur Halacha <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=50535&st=&pgnum=88">Tinyana</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=50537&st=&pgnum=31">Tlisa'ah</a> in  Orach Chaim siman 18 as 12.85°.
         * Actual calculations show it to be slightly more than 12.9°, but the Birur Halacha indicates that 12.85° is a
         * slight <em>chumra</em> (on a <em>bedieved</em> time) VS the 12.9° that 57 minutes calculates as (a difference of
         * about 14 seconds at the equinox/equilux in Jerusalem). The <em>zman</em> of 12.9° is also mentioned in the Piskei
         * Tshuvos siman 18, page 190 (where a typo indicates that this is the degree equivalent to 60 minutes before sunrise,
         * when in fact at that point the sun is about 13.5° below the horizon). The 57 minute based time is mentioned by the
         * Minchas Yitzchak <a href="https://hebrewbooks.org/pdfpager.aspx?req=1601&st=&pgnum=21">vol. 9, siman 9</a> as 15 minutes
         * before <em>alos hashachar</em> (though he is not clear what location he refers to, and does not mention a degree-based
         * conversion). The Kaf Hachaim <a href="https://hebrewbooks.org/pdfpager.aspx?req=8140&st=&pgnum=81">vol.1 siman 18, no.
         * 18</a> states that in Yerushalayim 60 fixed minutes are used year round. Calculations show that 60 fixed minutes in
         * Yerushalayim ranges from 13.5° at the spring equinox to 11.5° at the summer solstice. 57-minute
         * <em>misheyakir</em> range from 12.9° at the winter equinox to 11° at the summer solstice.
         * Analysis of the difference between 12.85° and 12.9°, shows that the maximum difference occurs at the summer
         * solstice. In Lakewood, NJ at a latitude of 40.096°, the maximum difference throughout the year is 23 seconds.
         * In the winter where there is the greatest need for very early <em>misheyakir</em> times, the difference is in the 16
         * second range. Going north to Montreal at latitude 45.5°, the maximum is 29 seconds and is about 18 seconds in the
         * winter. Moving farther north to the latitude of Vilnius at a latitude of 54.68°, things change. Firstly, around the
         * summer solstice it will not reach that far below the horizon. On the dates that both can be calculated, the maximum
         * difference can be pretty high on one or two days of the year (around Jul 8),  with about a week having over a two minute
         * difference between the two. Even at the latitude of Vilna, from Dec - March, the difference is about 22 seconds.
         * 
         * @deprecated This method returns a very early <em>misheyakir</em> time that should only be used <b><em>bish'as
         *         hadchak</em></b>. <em>Lechatchila</em>, a later <em>zman</em> should be used. There is no current plan to remove
         *         this method from the API, and this deprecation is intended to notify developers to add an alert to users of
         *         the risk of using it.
         * @return The {@code Instant} 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} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_12_POINT_85
         */
        @Deprecated (forRemoval=false)
        public Instant getMisheyakir12Point85Degrees() {
                return getSunriseOffsetByDegrees(ZENITH_12_POINT_85);
        }

        /**
         * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link #ZENITH_11_DEGREES
         * 11.5°} below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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()} 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° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH}.
         * @todo recalculate.
         * @return the {@code Instant} 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} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_11_POINT_5
         */
        public Instant 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°} below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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()} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
         * which calculates to 11° below {@link AstronomicalCalendar#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}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_11_DEGREES
         */
        public Instant 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°} below
         * {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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()} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox</a> which calculates
         * to 10.2° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH}.
         * 
         * @return the {@code Instant} 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} will be returned
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_10_POINT_2
         */
        public Instant 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°} below
         * {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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°. <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 Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_7_POINT_65
         * @see #getMisheyakir9Point5Degrees()
         */
        public Instant 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°} below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°). 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°. 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 Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_9_POINT_5
         * @see #getMisheyakir7Point65Degrees()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos19Point8Degrees() 19.8°} before {@link #getSunrise()}. 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° below sunrise or sunset. This returns the time of 3 *
         * {@link #getShaahZmanis19Point8Degrees()} after {@link #getAlos19Point8Degrees() dawn}.
         * 
         * @return the {@code Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis19Point8Degrees()
         * @see #getAlos19Point8Degrees()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos16Point1Degrees() 16.1°} before {@link #getSunrise()}. 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° below sunrise or sunset.
         * This returns the time of 3 * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() dawn}.
         * 
         * @return the {@code Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getAlos16Point1Degrees()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos18Degrees() 18°} before {@link #getSunrise()}. 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°
         * below sunrise or sunset. This returns the time of 3 * {@link #getShaahZmanis18Degrees()} after
         * {@link #getAlos18Degrees() dawn}.
         * 
         * @return the {@code Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis18Degrees()
         * @see #getAlos18Degrees()
         */
        public Instant getSofZmanShmaMGA18Degrees() {
                return getSofZmanShma(getAlos18Degrees(), getTzais18Degrees(), 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_Gombiner">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()}. 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 Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72MinutesZmanis()
         * @see #getAlos72Zmanis()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos90Minutes() 90} minutes before {@link #getSunrise()}. This time is 3
         * {@link #getShaahZmanis90Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos90Minutes() dawn} based on
         * the opinion of the MGA that the day is calculated from a {@link #getAlos90Minutes() dawn} of 90 minutes before sunrise to
         * {@link #getTzais90Minutes() nightfall} of 90 minutes after sunset. This returns the time of 3 *
         * {@link #getShaahZmanis90Minutes()} after {@link #getAlos90Minutes() dawn}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90Minutes()
         * @see #getAlos90Minutes()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Instant getSofZmanShmaMGA90Minutes() {
                return getSofZmanShma(getAlos90Minutes(), getTzais90Minutes(), 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_Gombiner">Magen Avraham (MGA)</a> based
         * on <em>alos</em> being {@link #getAlos90Zmanis() 90} minutes <em>zmaniyos</em> before {@link #getSunset()
         * 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 Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90MinutesZmanis()
         * @see #getAlos90Zmanis()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos96Minutes() 96} minutes before {@link #getSunrise()}. This time is 3 {@link
         * #getShaahZmanis96Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos96Minutes() dawn} based on the opinion
         * of the MGA that the day is calculated from a {@link #getAlos96Minutes() dawn} of 96 minutes before sunrise to {@link
         * #getTzais96Minutes() nightfall} of 96 minutes after sunset. This returns the time of 3 * {@link #getShaahZmanis96Minutes()}
         * after {@link #getAlos96Minutes() dawn}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis96Minutes()
         * @see #getAlos96Minutes()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Instant getSofZmanShmaMGA96Minutes() {
                return getSofZmanShma(getAlos96Minutes(), getTzais96Minutes(), 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos90Zmanis() 96} minutes <em>zmaniyos</em> before {@link #getSunrise()}. 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 Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis96MinutesZmanis()
         * @see #getAlos96Zmanis()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Instant 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 #getChatzosHayom()}. 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>.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getChatzosHayom()
         * @see #getSofZmanTfila2HoursBeforeChatzos()
         * @see #isUseAstronomicalChatzos()
         */
        public Instant getSofZmanShma3HoursBeforeChatzos() {
            return getTimeOffset(getChatzosHayom(), Duration.ofHours(-3));
        }

        /**
         * 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos120Minutes() 120} minutes or 1/6th of the day before {@link #getSunrise()}. This time is 3 {@link
         * #getShaahZmanis120Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos120Minutes() dawn} based on the
         * opinion of the MGA that the day is calculated from a {@link #getAlos120Minutes() dawn} of 120 minutes before sunrise to {@link
         * #getTzais120Minutes() nightfall} of 120 minutes after sunset. This returns the time of 3 {@link #getShaahZmanis120Minutes()}
         * after {@link #getAlos120Minutes() dawn}. This is an extremely early <em>zman</em> that is very much a <em>chumra</em>.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis120Minutes()
         * @see #getAlos120Minutes()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Instant getSofZmanShmaMGA120Minutes() {
                return getSofZmanShma(getAlos120Minutes(), getTzais120Minutes(), 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°} and ends at {@link
         * #getSeaLevelSunset() sea level sunset}. This is the opinion of the <a href=
         * "https://hebrewbooks.org/40357">חידושי וכללות הרז״ה</a> in <a href="https://hebrewbooks.org/pdfpager.aspx?req=40357&pgnum=71"
         * >סימן ב׳ סע״ג וסע״ד</a> and <a href="https://hebrewbooks.org/pdfpager.aspx?req=40357&pgnum=93">סימן ז׳ סע״ב</a> and the <a href=
         * "https://hebrewbooks.org/14799">מנורה הטהורה</a> as mentioned by <span lang="he">ישראל והזמנים</span> <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=9765&pgnum=81">ח״א סי׳ ז׳ פ״ג או׳ ט״ז</a>. Also see <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=67890&pgnum=29">אשר לשלמה, מועד, סי׳ ה׳</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()} based on the opinion that the day is calculated from
         * <em>alos</em> 16.1° to {@link #getSeaLevelSunset()}. <b>Note: </b> Based on this calculation <em>chatzos</em> will not be at
         * midday and {@link #isUseAstronomicalChatzosForOtherZmanim()} will be ignored. Sources for an asymmetrical day-based
         * calculation can be seen in the documentation of {@link #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees}.
         * 
         * @return the {@code Instant} 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 Instant getSofZmanShmaAlos16Point1ToSunset() {
                return getSofZmanShma(getAlos16Point1Degrees(), getSunsetBasedOnElevationSetting(), 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 is an asymmetrical day that starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ends at {@link
         * #getTzaisGeonim7Point083Degrees() <em>tzais</em> 7.083°}. 3 <em>shaos zmaniyos</em> (temporal hours) are calculated based on
         * this day and added to {@link #getAlos16Point1Degrees() <em>alos</em>} to reach this time. Sefer <a href=
         * "https://hebrewbooks.org/9765">Yisroel</a> <a href="https://hebrewbooks.org/9764">Vehazmanim</a> V. III in the explanation of
         * <a href="https://hebrewbooks.org/pdfpager.aspx?req=9764&st=&pgnum=260"><em>zman</em> no. 22 on page 1015</a> attributes the
         * origin of this <em>zman</em> to <a href="https://en.wikipedia.org/wiki/Jacob_al-Faraji">Rabbi Yaakov al-Faraji's</a> <a href=
         * "https://hebrewbooks.org/1151">שו״ת מהרי״ף</a> (who discusses <em>zmanim</em> in various places including chapters 6, 46, 47
         * and 49), <a href="https://en.wikipedia.org/wiki/Joseph_Schwarz_(geographer)">Rabbi Yehosef Schwarz</a> in the <a href=
         * "https://hebrewbooks.org/31703">דברי יוסף</a> in the name of <a href="https://en.wikipedia.org/wiki/Nathan_Adler"
         * >Rabbi Nosson Adler</a>, the <a href="https://en.wikipedia.org/wiki/Yosef_Hayyim">Ben Ish Chai</a> in <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=14054&st=&pgnum=108">שנה א׳ פ׳ ויקהל</a>, <a href=
         * "https://he.wikipedia.org/wiki/%D7%A0%D7%A1%D7%99%D7%9D_%D7%9B%D7%93%D7%95%D7%A8%D7%99_%D7%97%D7%96%D7%9F">Rabbi Nissim
         * Kaduri Chazan's</a> <a href="https://www.nli.org.il/he/books/NNL_ALEPH990019649990205171/NLI">מעשה נסים</a> (in the calendar at
         * the end), <a href="https://he.wikipedia.org/wiki/%D7%9E%D7%A6%D7%9C%D7%99%D7%97_%D7%9E%D7%90%D7%96%D7%95%D7%96">Rabbi Matzliach
         * Mazuz's</a> שו״ת איש מצליח, in Dr. Baruch (Berthold) Cohn's <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>, שו״ת תשובות והנהגות ח״א <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=20025&st=&pgnum=50">no. 55</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=20025&st=&pgnum=218">307</a> (<em>lechumra</em> in the name of the <a href=
         * "https://en.wikipedia.org/wiki/Yehoshua_Leib_Diskin">מהרי״ל דיסקין</a> and others) who calculate <em>shaos zmaniyos</em> based on
         * an asymmetrical day from an early <em>alos</em> to an early <em>tzais</em> <b>Note: </b> Based on this calculation
         * <em>chatzos</em> will not be at midday and {@link #isUseAstronomicalChatzosForOtherZmanim()} will be ignored. There are many
         * variations of this type of zman, with varying start and end times. The Yisroel Vehazmanim gave this as a relatively common one.
         * Variations using this library are very simple. For example to calculate <em>sof zman krias shema</em> starting the day at the
         * Rambam's alos of 18° and ending it at 3.7°, use the following code.
         * {@snippet lang='java' :
         * Instant sofZmanKS = czc.getSofZmanShma(czc.getAlos18Degrees(), czc.getTzaisGeonim3Point7Degrees(), false);
         * }
         * 
         * @return the {@code Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos16Point1Degrees()
         * @see #getTzaisGeonim7Point083Degrees()
         * @see #getPlagAlos16Point1DegreesToTzaisGeonim7Point083Degrees()
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim7Point083Degrees()
         */
        public Instant getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees() {
                return getSofZmanShma(getAlos16Point1Degrees(), getTzaisGeonim7Point083Degrees(), false);
        }

        /**
         * 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos19Point8Degrees() 19.8°} before {@link #getSunrise()}. This time is 4 {@link #getShaahZmanis19Point8Degrees()} after
         * {@link #getAlos19Point8Degrees()} based on the opinion that the day is calculated from dawn to nightfall with both being 19.8°
         * below sunrise or sunset.
         * 
         * @return the {@code Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis19Point8Degrees()
         * @see #getAlos19Point8Degrees()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on * <em>alos</em> being {@link
         * #getAlos16Point1Degrees() 16.1°} before {@link #getSunrise()}. This time is 4 {@link #getShaahZmanis16Point1Degrees()} after
         * {@link #getAlos16Point1Degrees()} based on the opinion that the day is calculated from dawn to nightfall with both being 16.1°
         * below sunrise or sunset.
         * 
         * @return the {@code Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getAlos16Point1Degrees()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos18Degrees()} before {@link #getSunrise()}. This time is 4 {@link #getShaahZmanis18Degrees()} after {@link
         * #getAlos18Degrees() dawn} based on the opinion that the day is calculated from dawn to nightfall with both being 18° below
         * sunrise and sunset.
         * 
         * @return the {@code Instant} 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} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis18Degrees()
         * @see #getAlos18Degrees()
         */
        public Instant getSofZmanTfilaMGA18Degrees() {
                return getSofZmanTfila(getAlos18Degrees(), getTzais18Degrees(), 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos72Zmanis()} 72 minutes <em>zmaniyos</em> or a 10th of the day before {@link #getSunrise()}. This time
         * is 4 {@link #getShaahZmanis72MinutesZmanis()} after {@link #getAlos72Zmanis()} based on the opinion that the day is calculated
         * from a {@link #getAlos72Zmanis()} before sunrise to {@link #getTzais72Zmanis()} of 72 minutes <em>zmaniyos</em> after sunset.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72MinutesZmanis()
         * @see #getAlos72Zmanis()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos90Minutes()} minutes before {@link #getSunrise()}. This time is 4 {@link #getShaahZmanis90Minutes()} after {@link
         * #getAlos90Minutes()} based on the opinion that the day is calculated from a {@link #getAlos90Minutes()} before sunrise to
         * {@link #getTzais90Minutes()} after sunset.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90Minutes()
         * @see #getAlos90Minutes()
         */
        public Instant getSofZmanTfilaMGA90Minutes() {
                return getSofZmanTfila(getAlos90Minutes(), getTzais90Minutes(), 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos90Zmanis()} 90 minutes <em>zmaniyos</em> or 1/8th of the day before {@link #getSunrise()}. This time is 4 {@link
         * #getShaahZmanis90MinutesZmanis()} after {@link #getAlos90Zmanis()} based on the opinion that the day is calculated from a {@link
         * #getAlos90Zmanis()} to {@link #getTzais90Zmanis()}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90MinutesZmanis()
         * @see #getAlos90Zmanis()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on
         * <em>alos</em> being {@link #getAlos96Minutes()} minutes before {@link #getSunrise()}. This time is 4
         * {@link #getShaahZmanis96Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos96Minutes() dawn} based on
         * the opinion of the MGA that the day is calculated from a {@link #getAlos96Minutes() dawn} of 96 minutes before
         * sunrise to {@link #getTzais96Minutes() nightfall} of 96 minutes after sunset. This returns the time of 4 *
         * {@link #getShaahZmanis96Minutes()} after {@link #getAlos96Minutes() dawn}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis96Minutes()
         * @see #getAlos96Minutes()
         */
        public Instant getSofZmanTfilaMGA96Minutes() {
                return getSofZmanTfila(getAlos96Minutes(), getTzais96Minutes(), 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos96Zmanis()} 96 minutes <em>zmaniyos</em> before {@link #getSunrise()}. This time is 4 {@link
         * #getShaahZmanis96MinutesZmanis()} after {@link #getAlos96Zmanis()} based on the opinion that the day is calculated from a
         * {@link #getAlos96Zmanis()} before sunrise to {@link #getTzais96Zmanis()} after sunset. This returns the time of 4 * {@link
         * #getShaahZmanis96MinutesZmanis()} after {@link #getAlos96Zmanis()}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90MinutesZmanis()
         * @see #getAlos90Zmanis()
         */
        public Instant 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos120Minutes()} before {@link #getSunrise()} . This time is 4 {@link #getShaahZmanis120Minutes()} after {@link
         * #getAlos120Minutes()} based on the opinion that the day is calculated from a {@link #getAlos120Minutes()}, 120 minutes before
         * sunrise to {@link #getTzais120Minutes()}, 120 minutes after sunset. This is an extremely early <em>zman</em> that is very
         * stringent <em>chumra</em>.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis120Minutes()
         * @see #getAlos120Minutes()
         */
        public Instant getSofZmanTfilaMGA120Minutes() {
                return getSofZmanTfila(getAlos120Minutes(), getTzais120Minutes(), true);
        }

        /**
         * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) calculated as 2 hours before {@link
         * #getChatzosHayom()}. 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 #getChatzosHayom()}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getChatzosHayom()
         * @see #getSofZmanShma3HoursBeforeChatzos()
         */
        public Instant getSofZmanTfila2HoursBeforeChatzos() {
                return getTimeOffset(getChatzosHayom(), Duration.ofHours(-2));
        }

        /**
         * This method returns <em>mincha gedola</em> calculated as 30 minutes after {@link #getChatzosHayom() <em>chatzos</em>}
         * and not 1/2 of a {@link #getShaahZmanisGRA() <em>shaah zmanis</em>} after {@link #getChatzosHayom() <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(Instant)} 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 #getMinchaGedolaGRA() <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}, this <em>mincha gedola</em> time will be affected by
         * {@link #isUseAstronomicalChatzos()} and not by {@link #isUseAstronomicalChatzosForOtherZmanim()}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @todo Consider adjusting this to calculate the time as half an hour after {@link #getChatzosHayom()} that uses
         *         {@link #isUseAstronomicalChatzos()} to determine the type of <em>chatzos</em> to utilize. that support it,
         *         based on {@link #isUseAstronomicalChatzos()}.
         * @see #getMinchaGedolaGRA()
         * @see #getMinchaGedolaGreaterThan30(Instant)
         * @see #getChatzosHayom()
         * @see #isUseAstronomicalChatzos()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         */
        public Instant getMinchaGedola30Minutes() {
                return getTimeOffset(getChatzosHayom(), Duration.ofMinutes(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 #getMinchaGedolaGRA() <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 #getAlos72Minutes() <em>alos</em>}. If {@link
         * #isUseAstronomicalChatzosForOtherZmanim()} is set to {@code true}, the calculation will be based on 0.5
         * {@link #getHalfDayBasedShaahZmanis(Instant, Instant) half-day based <em>sha'ah zmanis</em>} between
         * {@link #getChatzosHayom()} and {@link #getTzais72Minutes()} after {@link #getChatzosHayom()}.
         * 
         * @see #getAlos72Minutes()
         * @see #getMinchaGedolaGRA()
         * @see #getMinchaKetanaGRA()
         * @see #getMinchaGedolaGRA()
         * @see #getChatzosHayom()
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null}
         *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant getMinchaGedola72Minutes() {
                if (isUseAstronomicalChatzosForOtherZmanim()) {
                        return getHalfDayBasedZman(getChatzosHayom(), getTzais72Minutes(), 0.5);
                } else {
                        return getMinchaGedola(getAlos72Minutes(), getTzais72Minutes(), true);
                }
        }

        /**
         * This method returns the time of <em>mincha gedola</em> according to the Magen Avraham with the day starting and ending 16.1°
         * below the horizon. This is the earliest time to pray <em>mincha</em>. For more information on <em>mincha gedola</em>, see
         * {@link #getMinchaGedolaGRA()}. This is calculated as 6.5 {@link #getShaahZmanis16Point1Degrees()} after <em>alos</em>. If
         * {@link #isUseAstronomicalChatzosForOtherZmanim()} is set to {@code true}, the calculation will be based on 0.5 {@link
         * #getHalfDayBasedShaahZmanis(Instant, Instant) half-day based <em>sha'ah zmanis</em>} between {@link #getChatzosHayom()} and
         * {@link #getAlos16Point1Degrees()} after {@link #getChatzosHayom()}.
         * @return the {@code Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getMinchaGedolaGRA()
         * @see #getMinchaKetanaGRA()
         */
        public Instant getMinchaGedola16Point1Degrees() {
                if (isUseAstronomicalChatzosForOtherZmanim()) {
                        return getHalfDayBasedZman(getChatzosHayom(), 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 at {@link #getAlos16Point1Degrees()} and
         * ending at {@link #getTzaisGeonim3Point7Degrees()}. The later of this time or 30 clock minutes after <em>chatzos</em> is
         * returned. See {@link #getMinchaGedolaGreaterThan30(Instant)} for a way to calculate the later of 30 minutes or this <em>mincha
         * gedola</em>. For more information about <em>mincha gedola</em> see the documentation on {@link #getMinchaGedolaGRA()
         * <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. Sources for an asymmetrical day-based
         * calculation can be seen in the documentation of {@link #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees}.
         * @return the {@code Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos16Point1Degrees()
         * @see #getTzaisGeonim3Point7Degrees()
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point7Degrees()
         * @see #getMinchaGedolaGreaterThan30(Instant)
         */
        public Instant getMinchaGedolaAhavatShalom() {
        Instant chatzos = getChatzosHayom();
        Instant minchaGedola30 = getMinchaGedola30Minutes();
        Duration shaahZmanis = getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point7Degrees();
        
        if (chatzos == null || minchaGedola30 == null || shaahZmanis == null) {
                return null;
        }
        
        Instant minchaGedolaAhavatShalom = getTimeOffset(chatzos, shaahZmanis.dividedBy(2));
        return minchaGedola30.compareTo(minchaGedolaAhavatShalom) > 0 ? minchaGedola30 : minchaGedolaAhavatShalom;
        }

        /**
         * This is a convenience method that returns the later of the mincha gedola passed in 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 the mincha gedola passed in 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}, this <em>mincha</em>
         * time may be affected by {@link #isUseAstronomicalChatzos()}.
         * 
         * @param minchaGedola the mincha gedola to be compared to {@link #getMinchaGedola30Minutes()}.
         * @return the {@code Instant} of the later of {@link #getMinchaGedolaGRA()} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getMinchaGedolaGRA()
         * @see #getMinchaGedola30Minutes()
         * @see #isUseAstronomicalChatzos()
         * 
         */
        public Instant getMinchaGedolaGreaterThan30(Instant minchaGedola) {
                if (getMinchaGedola30Minutes() == null || minchaGedola == null) {
                        return null;
                } else {
                        return getMinchaGedola30Minutes().compareTo(minchaGedola) > 0 ? getMinchaGedola30Minutes()
                                        : minchaGedola;
                }
        }
        
        /**
         * This is a convenience method that returns the later of {@link #getMinchaGedolaGRA()} 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 #getMinchaGedolaGRA()} 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}, this <em>mincha</em> time may be affected by
         * {@link #isUseAstronomicalChatzos()}.
         * 
         * @return the {@code Instant} of the later of {@link #getMinchaGedolaGRA()} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @todo Consider adjusting this to calculate the time as 30 minutes after {@link #getChatzosHayom()} that uses {@link
         *         isUseAstronomicalChatzos()} to determine the type of <em>chatzos</em> to utilize (if the {@link
         *         com.kosherjava.zmanim.util.AstronomicalCalculator calculator} support astronomical <em>chatzos</em>),
         *         based on the {@link #isUseAstronomicalChatzos()} setting.
         * @see #getMinchaGedolaGRA()
         * @see #getMinchaGedola30Minutes()
         * @see #getMinchaGedolaGreaterThan30(Instant)
         * @see #isUseAstronomicalChatzos()
         */
        public Instant getMinchaGedolaGRAGreaterThan30() {
                return getMinchaGedolaGreaterThan30(getMinchaGedolaGRA());
        }

        /**
         * This method returns the time of <em>mincha ketana</em> according to the Magen Avraham with the day starting and ending 16.1°
         * 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 <em>mincha ketana</em> see the
         * documentation on {@link #getMinchaGedolaGRA()}. This is calculated as 9.5 {@link #getShaahZmanis16Point1Degrees()} after
         * {@link #getAlos16Point1Degrees()}.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getMinchaGedolaGRA()
         * @see #getMinchaKetanaGRA()
         * @return the {@code Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant 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()} with <em>shaos zmaniyos</em> calculated based on a day starting at {@link
         * #getAlos16Point1Degrees()} and ending at {@link #getTzaisGeonim3Point8Degrees()}. <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 <em>mincha ketana</em> see the documentation on {@link #getMinchaKetanaGRA()}.
         * 
         * @return the {@code Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point8Degrees()
         * @see #getMinchaGedolaAhavatShalom()
         * @see #getPlagAhavatShalom()
         */
        public Instant getMinchaKetanaAhavatShalom() {
                Duration shaahZmanis = getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point8Degrees();
                if(shaahZmanis == null) {
                        return null;
                }
                long totalNanos = (long) (-shaahZmanis.toNanos() * 2.5);
                return getTimeOffset(getTzaisGeonim3Point8Degrees(), Duration.ofNanos(totalNanos));
        }

        /**
         * 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 #getMinchaGedolaGRA()}. This is calculated as 9.5 {@link #getShaahZmanis72Minutes()} after
         * <em>alos</em>.
         * 
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getMinchaGedolaGRA()
         * @see #getMinchaKetanaGRA()
         * @return the {@code Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Instant getMinchaKetana72Minutes() {
                return getMinchaKetana(getAlos72Minutes(), getTzais72Minutes(), 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 {@link #getShaahZmanis60Minutes()}
         * after {@link #getAlos60Minutes()}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis60Minutes()
         * @see #getAlos60Minutes()
         * @see #getTzais60Minutes()
         */
        public Instant getPlagHamincha60Minutes() {
                return getPlagHamincha(getAlos60Minutes(), getTzais60Minutes(), 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 {@link #getShaahZmanis72Minutes()} after {@link #getAlos72Minutes()}. 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 Instant} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72Minutes()
         */
        @Deprecated (forRemoval=false)
        public Instant getPlagHamincha72Minutes() {
                return getPlagHamincha(getAlos72Minutes(), getTzais72Minutes(), 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 *
         * {@link #getShaahZmanis90Minutes()} after {@link #getAlos90Minutes()}. 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 Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis90Minutes()
         */
        @Deprecated (forRemoval=false)
        public Instant getPlagHamincha90Minutes() {
                return getPlagHamincha(getAlos90Minutes(), getTzais90Minutes(), 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
         * {@link #getShaahZmanis96Minutes()} after {@link #getAlos96Minutes()}. Since <em>plag</em> by this calculation can occur after
         * <em>shkiah</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 Instant} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis96Minutes()
         */
        @Deprecated (forRemoval=false)
        public Instant getPlagHamincha96Minutes() {
                return getPlagHamincha(getAlos96Minutes(), getTzais96Minutes(), 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 * {@link #getAlos96Zmanis()} after {@link #getAlos96Zmanis() dawn}. Since <em>plag</em> by this calculation can occur
         * after <em>shkiah</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 Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        @Deprecated (forRemoval=false)
        public Instant 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 Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        @Deprecated (forRemoval=false)
        public Instant 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 Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        @Deprecated (forRemoval=false)
        public Instant 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()} and ends at {@link #getTzais16Point1Degrees()}. This is calculated as 10.75 *
         * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees()}. Since <em>plag</em> by this calculation can
         * occur after <em>shkiah</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 Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis16Point1Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant 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()} and ends at {@link #getTzais19Point8Degrees()}. This is calculated as 10.75 *
         * {@link #getShaahZmanis19Point8Degrees()} after {@link #getAlos19Point8Degrees() dawn}. Since <em>plag</em> by this calculation
         * can occur after <em>shkiah</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 Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis19Point8Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant 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()} and ends at {@link #getTzais26Degrees()}. This is calculated as
         * 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 Instant} 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} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis26Degrees()
         * @see #getPlagHamincha120Minutes()
         */
        @Deprecated (forRemoval=false)
        public Instant 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()} and ends at {@link #getTzais18Degrees()}. This is calculated as 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 Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis18Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant 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()} and ends at {@link #getSunsetBasedOnElevationSetting}. This time is 10.75 *
         * <em>shaos zmaniyos</em> after {@link #getAlos16Point1Degrees()}. Since <em>plag</em> by this calculation can occur after
         * <em>shkiah</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 Instant} 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} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getAlos16Point1Degrees()
         * @see #getSeaLevelSunset()
         */
        @Deprecated (forRemoval=false)
        public Instant getPlagAlosToSunset() {
                return getPlagHamincha(getAlos16Point1Degrees(), getSunsetBasedOnElevationSetting(), false);
        }

        /**
         * This method returns the time of <em>plag hamincha</em> based on the opinion that the day starts at {@link
         * #getAlos16Point1Degrees()} and ends at {@link #getTzaisGeonim7Point083Degrees()}. The time is 10.75 * {@link
         * #getShaahZmanisAlos16Point1DegreesToTzaisGeonim7Point083Degrees()} after {@link #getAlos16Point1Degrees()} to reach this time.
         * Sources for an asymmetrical day-based calculation can be seen in the documentation of
         * {@link #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees}.
         * 
         * @return the {@code Instant} 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} will be returned. See detailed explanation on top of the {@link
         *         AstronomicalCalendar} documentation.
         * @see #getAlos16Point1Degrees()
         * @see #getTzaisGeonim7Point083Degrees()
         * @see #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees()
         */
        public Instant getPlagAlos16Point1DegreesToTzaisGeonim7Point083Degrees() {
                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 * {@link
         * #getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point8Degrees} before {@link #getTzaisGeonim3Point8Degrees()}. Sources for an
         * asymmetrical day-based calculation can be seen in the documentation of
         * {@link #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees}.
         * 
         * @return the {@code Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point8Degrees()
         * @see #getMinchaGedolaAhavatShalom()
         * @see #getMinchaKetanaAhavatShalom()
         */
        public Instant getPlagAhavatShalom() {
        Duration shaahZmanis = getShaahZmanisAlos16Point1DegreesToTzaisGeonim3Point8Degrees();
        if(shaahZmanis == null) {
                return null;
        }
        long totalNanos = (long) (-shaahZmanis.toNanos() * 1.25);
        return getTimeOffset(getTzaisGeonim3Point8Degrees(), Duration.ofNanos(totalNanos));
        }

        /**
         * 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°} below the western {@link AstronomicalCalendar#GEOMETRIC_ZENITH geometric horizon} (90°)
         * 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° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH}.
         * NOTE: As per Yisrael Vehazmanim Vol. III page 1025, No. 50, a dip of slightly less than 13° should be used.
         * Calculations show that the proper dip to be 13.2456° (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° versus 13°. For NY during the solstice, the difference is 1 minute 56 seconds.
         * 
         * @todo recalculate the above based on equilux/equinox calculations.
         * @return the {@code Instant} of the sun being 13.24° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH}
         *         (90°). 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} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getBainHashmashosRT58Point5Minutes()
         */
        public Instant getBainHashmashosRT13Point24Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_13_POINT_24);
        }

        /**
         * 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_mile">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 Instant} 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 when the sun does not rise, and one where it does
         *         not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * 
         */
        public Instant getBainHashmashosRT58Point5Minutes() {
                long totalNanos = (long) (58.5 * MINUTE_NANOS);
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofNanos(totalNanos));
        }

        /**
         * 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_mile">mil</a>) before <em>shkiah</em> calculated as
         * {@link #getTzaisGeonim7Point083Degrees()}.
         * 
         * @return the {@code Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzaisGeonim7Point083Degrees()
         */
        public Instant getBainHashmashosRT13Point5MinutesBefore7Point083Degrees() {
                long totalNanos = (long) (-13.5 * MINUTE_NANOS);
                return getTimeOffset(getTzaisGeonim7Point083Degrees(), Duration.ofNanos(totalNanos));
        }

        /**
         * 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° 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 Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant getBainHashmashosRT2Stars() {
                Instant alos19Point8 = getAlos19Point8Degrees();
                Instant sunrise = getSunriseBasedOnElevationSetting();
                if (alos19Point8 == null || sunrise == null) {
                        return null;
                }
                Duration alosToSunrise = Duration.between(alos19Point8, sunrise);
                long totalNanos = (long) (alosToSunrise.toNanos() * (5 / 18d));
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofNanos(totalNanos));
        }
        
        /**
         * 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_mile">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 Instant} 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 when the sun does not rise, and one where it does
         *         not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getBainHashmashosYereim3Point05Degrees()
         */
        public Instant getBainHashmashosYereim18Minutes() {
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofMinutes(-18));
        }
        
        /**
         * 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° 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_mile">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° as opposed to the traditional 0.566°
         * 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 HaHalacha 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° 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>Bain Hashmashos</em></a>.
         * 
         * @todo recalculate based on equinox/equilux
         * @return the {@code Instant} of the sun's position 3.05° 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 when the sun does not
         *         rise, and one where it does not set, a {@code null} 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 Instant getBainHashmashosYereim3Point05Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_MINUS_3_POINT_05);
        }
        
        /**
         * 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_milet">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 Instant} 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 when the sun does not rise, and one where it does
         *         not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getBainHashmashosYereim2Point8Degrees()
         */
        public Instant getBainHashmashosYereim16Point875Minutes() {
                long totalNanos = (long) (-16.875 * MINUTE_NANOS);
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofNanos(totalNanos));
        }
        
        /**
         * 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°
         * 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 22.5-minute <a href="https://en.wikipedia.org/wiki/Biblical_mile"
         * >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 Instant} of the sun's position 2.8° 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 when the sun does not
         *         rise, and one where it does not set, a {@code null} 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 Instant getBainHashmashosYereim2Point8Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_MINUS_2_POINT_8);
        }
        
        /**
         * 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_mile">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 Instant} 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 when the sun does not rise, and one where it does
         *         not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getBainHashmashosYereim2Point1Degrees()
         */
        public Instant getBainHashmashosYereim13Point5Minutes() {
                long totalNanos = (long) (-13.5 * MINUTE_NANOS);
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofNanos(totalNanos));
        }
        
        /**
         * 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°
         * <b>above</b> 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_mile">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 Instant} of the sun's position 2.1° minutes before sunset. If the calculation can't be computed such as i
         *         the Arctic Circle where there is at least one day a year when the sun does not rise, and one where it does not set, a
         *         {@code null} 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 Instant getBainHashmashosYereim2Point1Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_MINUS_2_POINT_1);
        }
        
        /**
         * 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°} below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°), calculated as the position of the
         * sun 13.5 minutes after sunset, the time it takes to walk 3/4 of a <a href="https://en.wikipedia.org/wiki/Biblical_mile">mil</a>
         * at 18 minutes a mil, or 13.5 minutes after sunset. The sun is 3.7° below {@link AstronomicalCalendar#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>. This does not cover the 26.46 it takes to walk 49 amos (the <em>heref ayin</em> of <em>bain hashmashos</em> of
         * Rav Yosi) at the pace of an 18-minute mil. Rabbi Yedidya Manet in his <a href=
         * "https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei HaHalacha Lema'aseh</a> (5th edition, vol. I page 36, no. 22)
         * lists 3.65° as the value for this <em>tzais</em>, however it is based on sunset calculated using a refreaction value of 31′
         * (arcminutes) or 0.516° (page 16) based on his calculations of the refraction value in Israel at the autumn equinox (something
         * he himself questions in vol II, page 36). Even for Israel, most consider that refraction value too low. Regardless, the dip for
         * <em>tzais</em> must be based on sunset using a specific refraction model (and solar radius), and this library currently uses a
         * global average refraction value of 34′ (arcminutes) or 0.566°. Based on the global average refraction for sunset, this
         * <em>tzais</em> calculates as 3.7°.
         * 
         * @return the {@code Instant} representing the time when the sun is 3.7° below sea level.
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very early 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.
         * @see #ZENITH_3_POINT_7
         */
        @Deprecated (forRemoval=false)
        public Instant 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_7 3.8°} below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°), calculated as the position of the
         * sun 13.5 minutes after sunset, the time it takes to walk 3/4 of a <a href="https://en.wikipedia.org/wiki/Biblical_mile">mil</a>
         * at 18 minutes a mil, plus 30 seconds for the time it takes to walk 49 amos (the <em>heref ayin</em> of <em>bain hashmashos</em>
         * of Rav Yosi). With this being an 18-minutes mil, 49 amos would take 26.46, rounded to 30 seconds), for a total of 14 minutes
         * after sunset. The sun is {@link #ZENITH_3_POINT_8 3.8°} below {@link AstronomicalCalendar#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>.
         * 
         * @return the {@code Instant} representing the time when the sun is 3.8° below sea level.
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very early 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.
         * @see #ZENITH_3_POINT_8
         */
        @Deprecated (forRemoval=false)
        public Instant 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°} below {@link AstronomicalCalendar#GEOMETRIC_ZENITH} (90°), calculated as 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>. The 24 minutes
         * is based on the Baal Hatanya's calculation of 18 minutes (3/4 of a 24 minute mil) + 4 minutes for <em>shkiah amitis</em> +
         * 2 minutes for bain hashmashos of Rav Yosi. See Hazmanim Bahalacha vol II, ch. 50, no. 5, p. 512-513, ch. 47, and Yisrael
         * Vehazmanim <a href="https://hebrewbooks.org/pdfpager.aspx?req=9764&st=&pgnum=266">Vol III, ch. 13, no. 53, p. 1026</a>. Among
         * sources he mentions for this <em>zman</em> is <a href="https://en.wikipedia.org/wiki/Yehuda_(Leo)_Levi">Rabbi Yehuda (Leo)
         * Levi's</a> calculations in Jewish Chrononomy and other sources. Calculations show that the time is closer to 5.93° and was
         * seemingly rounded to 5.95°. Chabad calendars usually use the 6°-based {@link #getTzaisBaalHatanya()} that is built on this
         * same calculation. Rabbi Yedidya Manet in his <a href="https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei HaHalacha
         * Lema'aseh</a> (5th edition, vol. I page 36, no. 24) lists 5.88° as the value for this <em>tzais</em>, however it is based on
         * sunset calculated using a refreaction value of 31′ (arcminutes) or 0.516° (page 16) based on his calculations of the refraction
         * value in Israel at the autumn equinox (something he himself questions in vol II, page 36). Even for Israel, most consider that
         * refraction value too low. Regardless, the dip for <em>tzais</em> must be based on sunset using a specific refraction model
         * (and solar radius), and this library currently uses a global average refraction value of 34′ (arcminutes) or 0.566°. Based on
         * the global average refraction for sunset, this <em>tzais</em> calculates as 5.93° (rounded by most calendars to 5.95°).
         * 
         * @return the {@code Instant} representing the time when the sun is 5.95° 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzaisBaalHatanya()
         */
        public Instant 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_mile">mil</a> based on a 24-minute mil, or 18 minutes. It is the sun's position at
         * {@link #ZENITH_4_POINT_66 4.66°} below the western horizon. This is a very early <em>zman</em> and should not be relied on
         * without Rabbinical guidance. This does not cover the 35.28 seconds it takes to walk 49 amos (the <em>heref ayin</em> of
         * <em>bain hashmashos</em> of Rav Yosi) at the pace of a 24-minute mil. See {@link #getTzaisGeonim4Point8Degrees()} for a time
         * that covers the <em>heref ayin</em>. Rabbi Yedidya Manet in his <a href=
         * "https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei HaHalacha Lema'aseh</a> (5th edition, vol. I page 36, no. 24)
         * lists 4.61° as the value for this <em>tzais</em>, however it is based on sunset calculated using a refreaction value of 31′
         * (arcminutes) or 0.516° (page 16) based on his calculations of the refraction value in Israel at the autumn equinox (something
         * he himself questions in vol II, page 36). Even for Israel, most consider that refraction value too low. Regardless, the dip for
         * <em>tzais</em> must be based on sunset using a specific refraction model (and solar radius), and this library currently uses a
         * global average refraction value of 34′ (arcminutes) or 0.566°. Based on the global average refraction for sunset, this
         * <em>tzais</em> calculates as 4.66°.
         * 
         * @return the {@code Instant} representing the time when the sun is 4.66° 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very early 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.
         * @see #ZENITH_4_POINT_66
         * @see #getTzaisGeonim4Point8Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant getTzaisGeonim4Point66Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_4_POINT_66);
        }

        /**
         * 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_mile">mil</a>, based on a 22.5-minute mil, or 16.875 minutes. It is the sun's position
         * at {@link #ZENITH_4_POINT_42 4.42°} below the western horizon. This is a very early <em>zman</em> and should not be relied on
         * without Rabbinical guidance. This does not cover the 33.07 seconds it takes to walk 49 amos (the <em>heref ayin</em> of
         * <em>bain hashmashos</em> of Rav Yosi) at the pace of a 22.5 minute-mil. Rabbi Yedidya Manet in his <a href=
         * "https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei HaHalacha Lema'aseh</a> (5th edition, vol. I page 36, no. 23)
         * lists 4.37° as the value for this <em>tzais</em>, however it is based on sunset calculated using a refreaction value of 31′
         * (arcminutes) or 0.516° (page 16) based on his calculations of the refraction value in Israel at the autumn equinox (something
         * he himself questions in vol II, page 36). Even for Israel, most consider that refraction value too low. Regardless, the dip for
         * <em>tzais</em> must be based on sunset using a specific refraction model (and solar radius), and this library currently uses a
         * global average refraction value of 34′ (arcminutes) or 0.566°. Based on the global average refraction for sunset, this
         * <em>tzais</em> calculates as 4.42°.
         * 
         * @return the {@code Instant} representing the time when the sun is 4.42° 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} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @deprecated This method should be used <em>lechumra</em> only since it returns a very early 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.
         * @see #ZENITH_4_POINT_42
         */
        @Deprecated (forRemoval=false)
        public Instant getTzaisGeonim4Point42Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_4_POINT_42);
        }

        /**
         * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as the sun's
         * position below the horizon at a time of 18.6 minutes after sunset. This is calculated as 3/4 of a 24-minute <a href=
         * "https://en.wikipedia.org/wiki/Biblical_mile">mil</a>, plus 0.6 minutes for the time to walk 49 amos for <em>bain
         * hashmashos</em> of Rav Yosi (with this <em>zman</em> based on a 24-minute mil, 49 amos would take 35.28 seconds to walk), for
         * a total of 18.6 minutes after sunset. This calculates to the sun's position at {@link #ZENITH_4_POINT_8 4.8°} below the
         * western horizon. This is based on <a href=
         * "https://he.wikipedia.org/wiki/%D7%99%D7%97%D7%99%D7%90%D7%9C_%D7%9E%D7%99%D7%9B%D7%9C_%D7%A9%D7%9C%D7%96%D7%99%D7%A0%D7%92%D7%A8"
         * >Rav Yechiel Michel Shlezinger's</a> <em>sefer</em> <a href="https://www.nli.org.il/he/books/NNL_ALEPH997010042055805171/NLI"
         * >Aizehu Bain Hashmashos</a>, <a href="https://en.wikipedia.org/wiki/Yehuda_(Leo)_Levi">Rabbi Yehuda (Leo) Levi's</a>
         * calculations in <a href="https://www.nli.org.il/en/items/NNL_ALEPH990022548970205171/NLI">Zmanei Hayom BaHalacha</a> p. 37.
         * At this point, 3 medium sized stars are visible to a non-expert with good vision with effort. An expert knowing where to
         * look can see the 3 medium stars as early as 15 minutes after sunset. This is explained in detail in Hazmanim Bahalacha vol
         * II, ch. 41, no. 6 (p. 372-373, ch. 47, no. 11-12 (p. 491-493) where it is clear that medium sized stars would be visible as
         * early as 14 minutes after sunset (13.5 minutes for 3/4 of an 18 minute Mil, plus 0.5 minutes for <em>bain Hashmashos</em>
         * of Rav Yosi) to an expert. See more details on this earlier <em>zman</em> at {@link #getTzaisGeonim3Point8Degrees()}.
         * This is an early <em>zman</em> for <em>tzais</em>and should not be relied on without Rabbinical guidance.
         * 
         * @return the {@code Instant} representing the time when the sun is 4.8° 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_4_POINT_8
         */
        public Instant 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> as the position of
         * the sun no later than 31 minutes after sea-level sunset in Jerusalem (the Birur halacha shows that Rav Tucazinsky's
         * calculations for sunset, listed as 28 minutes in this case, were about 3 minutes later than reality), and at the height of
         * the summer solstice, this <em>zman</em>, calculations show that 30.75 minutes after <em>shkiah</em> computes to 6.45° below
         * {@link AstronomicalCalendar#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> and it is the commonly used
         * <em>zman</em> in Israel. It is also used in the <a href="https://www.worldcat.org/oclc/243303103">Luach Itim Lebinah</a>. it
         * should be noted that this differs from the 6.1° / 6.2° calculation for Rabbi Tucazinsky's time as calculated by the
         * Hazmanim Bahalacha Vol II chapter 50:7 (page 515). Calculations show that 6.45° at the equinox is 26.5 minutes after
         * <em>shkiah</em> <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox /
         * equilux</a>. 
         * 
         * @return the {@code Instant} representing the time when the sun is 6.45° 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} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_6_POINT_45
         */
        public Instant 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° (or 7° 5′}) below the western horizon. This is often referred to as 7° 5′ or 7° 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 <em>tzais</em> 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"
         * >שו״ת מלמד להועיל</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 שו״ת בני ציון and the <a href="https://hebrewbooks.org/67373">תנובת שדה</a>. It is very close to the time of the <a href=
         * "https://hebrewbooks.org/22044">מקור חסד</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°
         * and 7.199° at the equinox. See Hazmanim Bahalacha vol 2, pages 520-521 for more details.
         * 
         * @return the {@code Instant} representing the time when the sun is 7.083° 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_7_POINT_083
         */
        public Instant 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 7.67°} 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. 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 Instant} representing the time when the sun is 7.67° 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} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #ZENITH_7_POINT_67
         */
        public Instant getTzaisGeonim7Point67Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_7_POINT_67);
        }
        
        /**
         * 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
         * as the sun's position at {@link #ZENITH_9_POINT_3 9.3°} below the western horizon.
         * 
         * @return the {@code Instant} representing the time when the sun is 9.3° 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant 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°} 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 Instant} representing the time when the sun is 9.75° 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         *
         * @see #getTzais60Minutes()
         */
        public Instant 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_mile">mil</a> is 15 minutes, for a total of 60 minutes for 4 mil after {@link
         * #getSunsetBasedOnElevationSetting()}(depends on the {@link #isUseElevation()} setting). See detailed documentation explaining
         * the 60 minute concept at {@link #getAlos60Minutes()}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set,
         *         a {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * 
         * @see #getAlos60Minutes()
         * @see #getPlagHamincha60Minutes()
         * @see #getShaahZmanis60Minutes()
         */
        public Instant getTzais60Minutes() {
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofMinutes(60));
        }

        /**
         * 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 Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         */
        public Instant getTzaisAteretTorah() {
                long totalNanos = (long) (getAteretTorahSunsetOffset() * MINUTE_NANOS);
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofNanos(totalNanos));
        }
        
        /**
         * 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 Instant} 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 when the sun does not rise, and one where
         *         it does not set, a {@code null} 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 Instant 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()} to reach this time. This time is 4 * {@link #getShaahZmanisAteretTorah()} after {@link
         * #getAlos72Zmanis()}. <b>Note: </b> Based on this calculation <em>chatzos</em> will not be at midday. Sources for an
         * asymmetrical day-based calculation can be seen in the documentation of
         * {@link #getSofZmanShmaAlos16Point1DegreesToTzaisGeonim7Point083Degrees}.
         * 
         * @return the {@code Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Zmanis()
         * @see #getTzaisAteretTorah()
         * @see #getShaahZmanisAteretTorah()
         * @see #setAteretTorahSunsetOffset(double)
         */
        public Instant getSofZmanTfilaAteretTorah() {
                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 #getMinchaGedolaGRA() <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 #getMinchaGedolaGRA()
         * @see #getMinchaKetanaAteretTorah()
         * @see #getMinchaGedolaGRA()
         * @see #getAteretTorahSunsetOffset()
         * @see #setAteretTorahSunsetOffset(double)
         * @return the {@code Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Instant 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 #getMinchaGedolaGRA() <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 #getMinchaGedolaGRA()
         * @see #getMinchaKetanaGRA()
         * @return the {@code Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Instant 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 Instant} 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 when 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 Instant 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>tzais</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 Instant} 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 when the sun does not rise, and one where it does not set,
         *         a {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos72Zmanis()
         */
        public Instant getTzais72Zmanis() {
                return getZmanisBasedOffset(1.2);
        }

        /**
         * 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> used in various <em>kehilos</em>.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set,
         *         a {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos90Zmanis()
         */
        public Instant 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 Instant} 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 when the sun does not rise, and one where it does not set,
         *         a {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos96Zmanis()
         */
        public Instant getTzais96Zmanis() {
                return getZmanisBasedOffset(1.6);
        }

        /**
         * Method to return <em>tzais</em> (dusk) calculated as 90 minutes after {@link #getSunsetBasedOnElevationSetting} (depends on
         * the {@link #isUseElevation()} setting). 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_mile">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 elevation adjusted <em>shkiah</em> (sunset). A similar
         * calculation {@link #getTzais19Point8Degrees()} uses solar position* calculations based on this time.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set,
         *         a {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getTzais19Point8Degrees()
         * @see #getAlos90Minutes()
         */
        public Instant getTzais90Minutes() {
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofMinutes(90));
        }

        /**
         * 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_mile">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 {@link #getSunsetBasedOnElevationSetting()} (depends on the {@link #isUseElevation()}
         * setting). 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° 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 Instant} 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 when the sun does not rise, and one where it does not set,
         *         a {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}.
         *         documentation.
         * @see #getTzais26Degrees()
         * @see #getAlos120Minutes()
         */
        @Deprecated (forRemoval=false)
        public Instant getTzais120Minutes() {
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofMinutes(120));
        }

        /**
         * 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° 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 Instant} 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 when the sun does not rise, and one where it does not set,
         *         a {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos120Zmanis()
         * @see #getTzais120Minutes()
         * @see #getTzais26Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant getTzais120Zmanis() {
                return getZmanisBasedOffset(2.0);
        }

        /**
         * This calculates the time of <em>tzais</em> at the point when the sun is 16.1° 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 HaHalacha Lema'aseh</a> (4th edition part 2, pages
         * and 22 and 24) and Rabbi Yonah Mertzbuch (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 Instant} 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} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzais72Minutes()
         * @see #getAlos16Point1Degrees() for more information on this calculation.
         */
        public Instant 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°
         * 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° 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 Instant} 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} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzais120Minutes()
         * @see #getAlos26Degrees()
         */
        @Deprecated (forRemoval=false)
        public Instant getTzais26Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_26_DEGREES);
        }

        /**
         * For information on how this is calculated see the comments on {@link #getAlos18Degrees()}
         * 
         * @return the {@code Instant} 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} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos18Degrees()
         */
        public Instant getTzais18Degrees() {
                return getSunsetOffsetByDegrees(ASTRONOMICAL_ZENITH);
        }

        /**
         * For information on how this is calculated see the comments on {@link #getAlos19Point8Degrees()}.
         * 
         * @return the {@code Instant} 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} will be returned. See
         *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzais90Minutes()
         * @see #getAlos19Point8Degrees()
         */
        public Instant getTzais19Point8Degrees() {
                return getSunsetOffsetByDegrees(ZENITH_19_POINT_8);
        }

        /**
         * A method to return <em>tzais</em> (dusk) calculated as 96 minutes after {@link #getSunset() sunset} or {@link
         * #getSeaLevelSunset() sea level sunset} (depending on the {@link #isUseElevation()} setting). For information on how
         * this is calculated see the comments on {@link #getAlos96Minutes()}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set,
         *         a {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
         *         documentation.
         * @see #getAlos96Minutes()
         */
        public Instant getTzais96Minutes() {
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofMinutes(96));
        }

        /**
         * A method that returns the local time for fixed <em>chatzos</em>. This time is noon and adjusted from
         * standard time to account for the local latitude. The 360° of the globe divided by 24 calculates to 15°
         * 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°. 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° time zones, but will adjust to the actual time zone and <a
         * href="https://en.wikipedia.org/wiki/Daylight_saving_time">Daylight saving time</a>.
         * 
         * @return the Instant representing the local <em>chatzos</em>
         * @see GeoLocation#getLocalMeanTimeOffset(Instant)
         * @see #getLocalMeanTime(LocalTime)
         */
        public Instant getFixedLocalChatzosHayom() {
                return getLocalMeanTime(LocalTime.NOON);
        }

        /**
         * 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} <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 Instant 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} will be returned.
         * @see #getSofZmanKidushLevanaBetweenMoldos()
         * @see #getSofZmanKidushLevana15Days(Instant, Instant)
         * @see JewishCalendar#getSofZmanKidushLevanaBetweenMoldos()
         */
        public Instant getSofZmanKidushLevanaBetweenMoldos(Instant alos, Instant tzais) {
                JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
                
                // 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 Instant 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 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} will be
         *         returned.
         */
        private Instant getMoladBasedTime(Instant moladBasedTime, Instant alos, Instant tzais, boolean techila) {
                Instant lastMidnight = getMidnightLastNight().toInstant();
                Instant midnightTonight = getMidnightTonight().toInstant();
                if(moladBasedTime.isBefore(lastMidnight) || moladBasedTime.isAfter(midnightTonight)){ // Invalid time, bailout
                        return null;
                } else if (alos == null || tzais == null){ // Not enough info to adjust
                   return moladBasedTime;
                } else { // It's the daytime, get the next/prev night
                        if (moladBasedTime.isAfter(alos) && moladBasedTime.isBefore(tzais)) {
                                if (techila) {
                                        return tzais;
                                } else {
                                        return alos;
                                }
                        } else { // It's the night, the provided time is valid
                                return moladBasedTime;
                        }
                }
        }

        /**
         * 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(Instant, Instant)}.
         * 
         * @return the Instant representing the moment halfway between molad and molad. If the <em>zman</em> will not occur on this
         *         day, a {@code null} will be returned.
         * @see #getSofZmanKidushLevanaBetweenMoldos(Instant, Instant)
         * @see #getSofZmanKidushLevana15Days()
         * @see JewishCalendar#getSofZmanKidushLevanaBetweenMoldos()
         */
        public Instant 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(Instant, Instant) halfway 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 {@code null}, no daytime adjustment will be made.
         * @return the Instant 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} will be returned.
         * @see #getSofZmanKidushLevanaBetweenMoldos(Instant, Instant)
         * @see JewishCalendar#getSofZmanKidushLevana15Days()
         */
        public Instant getSofZmanKidushLevana15Days(Instant alos, Instant tzais) {
                JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
                
                // 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(Instant, Instant) halfway 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(Instant, Instant)}.
         * 
         * @return the Instant representing the moment 15 days after the <em>molad</em>. If the <em>zman</em> will not occur on this day,
         *         a {@code null} will be returned.
         * @see #getSofZmanKidushLevana15Days(Instant, Instant)
         * @see #getSofZmanKidushLevanaBetweenMoldos()
         * @see JewishCalendar#getSofZmanKidushLevana15Days()
         * 
         */
        public Instant 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(Instant, Instant)} if you want to limit the time to night hours.
         * 
         * @return the Instant representing the moment 3 days after the molad. If the <em>zman</em> will not occur on this day, a
         *         {@code null} will be returned.
         * @see #getTchilasZmanKidushLevana3Days(Instant, Instant)
         * @see #getTchilasZmanKidushLevana7Days()
         * @see JewishCalendar#getTchilasZmanKidushLevana3Days()
         */
        public Instant 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 Instant 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}
         *         will be returned.
         * @see #getTchilasZmanKidushLevana3Days()
         * @see #getTchilasZmanKidushLevana7Days(Instant, Instant)
         * @see JewishCalendar#getTchilasZmanKidushLevana3Days()
         */
        public Instant getTchilasZmanKidushLevana3Days(Instant alos, Instant tzais) {
                JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
                
                // 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;
                }
                
                Instant 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.plusMonths(1);
                        zman = getMoladBasedTime(jewishCalendar.getTchilasZmanKidushLevana3Days(), null, null, true);
                }
                
                return zman;
        }
        
        /**
         * Returns the point in time of <em>Molad</em> as a {@code Instant} Object. For the traditional day of week, hour,
         * minute and chalakim, {@link JewishCalendar#getMoladAsInstant()} and the not yet completed
         * {@link com.kosherjava.zmanim.hebrewcalendar.HebrewDateFormatter} that will have formatting for this.
         * 
         * @return the Instant representing the moment of the molad. If the <em>molad</em> does not occur on this day, a
         *         {@code null} will be returned.
         * @see #getTchilasZmanKidushLevana3Days()
         * @see #getTchilasZmanKidushLevana7Days(Instant, Instant)
         * @see JewishCalendar#getMoladAsInstant()
         */
        public Instant getZmanMolad() {
                JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
                
                // 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;
                }
                Instant molad = getMoladBasedTime(jewishCalendar.getMoladAsInstant(), null, null, true);

                // deal with molad that happens on the end of the previous month
                if (molad == null && jewishCalendar.getJewishDayOfMonth() > 26) {
                        jewishCalendar.plusMonths(1);
                        molad = getMoladBasedTime(jewishCalendar.getMoladAsInstant(), null, null, true);
                }
                return molad;
        }

        /**
         * 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 #getAlos72Minutes() <em>alos</em>} and {@link #getTzais72Minutes() <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 {@code null}, no daytime adjustment will be made.
         * @return the Instant 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} will be returned.
         * @see #getTchilasZmanKidushLevana3Days(Instant, Instant)
         * @see #getTchilasZmanKidushLevana7Days()
         * @see JewishCalendar#getTchilasZmanKidushLevana7Days()
         */
        public Instant getTchilasZmanKidushLevana7Days(Instant alos, Instant tzais) {
                JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
                
                // 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(Instant, Instant)} if you want to limit the time to night hours.
         * 
         * @return the Instant 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} will be returned.
         * @see #getTchilasZmanKidushLevana7Days(Instant, Instant)
         * @see JewishCalendar#getTchilasZmanKidushLevana7Days()
         * @see #getTchilasZmanKidushLevana3Days()
         */
        public Instant 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 {@code null} will be returned.
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisGRA()
         * @see #getSofZmanTfilaGRA()
         * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanAchilasChametzGRA() {
                return getSofZmanAchilasChametz(getSunriseBasedOnElevationSetting(), getSunsetBasedOnElevationSetting(), 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 <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos72Minutes() 72} minutes before {@link #getSunrise()}. This time is identical to the
         * {@link #getSofZmanTfilaMGA72Minutes() <em>Sof zman tfilah</em> MGA 72 minutes}. This time is 4 {@link
         * #getShaahZmanis72Minutes() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Minutes() dawn} based on the
         * opinion of the MGA that the day is calculated from a {@link #getAlos72Minutes() dawn} of 72 minutes before sunrise to {@link
         * #getTzais72Minutes() nightfall} of 72 minutes after sunset. This returns the time of 4 * {@link #getShaahZmanis72Minutes()}
         * after {@link #getAlos72Minutes() dawn}. If it is not <em>erev Pesach</em>, a {@code null} will be returned.
         * 
         * @return the {@code Instant} 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 when the sun does
         *         not rise, and one where it does not set, a {@code null} will be returned. See detailed explanation on top of
         *         the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72Minutes()
         * @see #getAlos72Minutes()
         * @see #getSofZmanTfilaMGA72Minutes()
         * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanAchilasChametzMGA72Minutes() {
                return getSofZmanAchilasChametz(getAlos72Minutes(), getTzais72Minutes(), 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 <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos72Zmanis() 72 zmaniyos} minutes before {@link #getSunrise()}. 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 #getAlos72Minutes() 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 {@code null}
         * will be
         * returned.
         *
         * @return the {@code Instant} 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 when the sun does
         *         not rise, and one where it does not set, a {@code null} will be returned. See detailed explanation on top of
         *         the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72MinutesZmanis()
         * @see #getAlos72Zmanis()
         * @see #getSofZmanTfilaMGA72MinutesZmanis()
         * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanAchilasChametzMGA72MinutesZmanis() {
                return getSofZmanAchilasChametz(getAlos72Zmanis(), getTzais72Zmanis(), 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 <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos16Point1Degrees() 16.1°} before {@link #getSunrise()}. This time is 4 {@link #getShaahZmanis16Point1Degrees()}
         * after {@link #getAlos16Point1Degrees()} based on the opinion of the MGA that the day is calculated from dawn to nightfall with
         * both being 16.1° 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 {@code null} will be returned.
         * 
         * @return the {@code Instant} 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} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getAlos16Point1Degrees()
         * @see #getSofZmanTfilaMGA16Point1Degrees()
         * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanAchilasChametzMGA16Point1Degrees() {
                return getSofZmanAchilasChametz(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
        }

        /**
         * 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 returns the time 5 * {@link #getShaahZmanisGRA()} after
         * {@link #getSeaLevelSunrise()}. If it is not  <em>erev Pesach</em>, a {@code null} will be returned.
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisGRA()
         * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanBiurChametzGRA() {
                return getSofZmanBiurChametz(getSunriseBasedOnElevationSetting(), getSunsetBasedOnElevationSetting(), true);
        }

        /**
         * 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos72Minutes() 72} minutes before {@link #getSunrise()}. This time is 5 {@link
         * #getShaahZmanis72Minutes() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Minutes() dawn} based on the
         * opinion of the MGA that the day is calculated from a {@link #getAlos72Minutes() dawn} of 72 minutes before sunrise to {@link
         * #getTzais72Minutes() nightfall} of 72 minutes after sunset. This returns the time of 5 * {@link #getShaahZmanis72Minutes()}
         * after {@link #getAlos72Minutes() dawn}. If it is not  <em>erev Pesach</em>, a {@code null} will be returned.
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72Minutes()
         * @see #getAlos72Minutes()
         * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanBiurChametzMGA72Minutes() {
                return getSofZmanBiurChametz(getAlos72Minutes(), getTzais72Minutes(), true);
        }
        
        /**
         * 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
         * #getAlos72Zmanis() 72} minutes zmanis before {@link #getSunrise()}. 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
         * {@code null} will be returned.
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis72MinutesZmanis()
         * @see #getAlos72Zmanis()
         * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanBiurChametzMGA72MinutesZmanis() {
                return getSofZmanBiurChametz(getAlos72Zmanis(), getTzais72Zmanis(), true);
        }

        /**
         * 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_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
         * being {@link #getAlos16Point1Degrees() 16.1°} before {@link #getSunrise()}. 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°
         * 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 {@code null} will be returned.
         * @return the {@code Instant} 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} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanis16Point1Degrees()
         * @see #getAlos16Point1Degrees()
         * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanBiurChametzMGA16Point1Degrees() {
                return getSofZmanBiurChametz(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
        }

        /**
         * 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(Instant, Instant) temporal hour}). This forms the base for the Baal Hatanya's day based
         * calculations that are calculated as a 1.583° 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° below the
         * horizon. A method that returns a <em>shaah zmanis</em> ({@link #getTemporalHour(Instant, Instant) 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° 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 Duration} 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 when the sun does not rise, and
         *         one where it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         * @see #getTemporalHour(Instant, Instant)
         * @see #getSunriseBaalHatanya()
         * @see #getSunsetBaalHatanya()
         * @see ZmanimCalendar#ZENITH_1_POINT_583
         */
        public Duration 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° below the eastern {@link AstronomicalCalendar#GEOMETRIC_ZENITH geometric horizon} before
         * {@link #getSunrise()}. 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° below {@link AstronomicalCalendar#GEOMETRIC_ZENITH}.
         * 
         * @return The {@code Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant 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 #getSofZmanShma(Instant, Instant)
         * @see #getShaahZmanisBaalHatanya()
         * @return the {@code Instant} 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 when the sun does
         *         not rise, and one where it does not set, a {@code null} will be returned. See detailed explanation on
         *         top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant 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 #getSofZmanTfila(Instant, Instant)
         * @see #getShaahZmanisBaalHatanya()
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does
         *         not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Instant 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 {@code null} will be returned.
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisBaalHatanya()
         * @see #getSofZmanTfilaBaalHatanya()
         * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanAchilasChametzBaalHatanya() {
                return getSofZmanAchilasChametz(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * 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 {@code null} will be returned.
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getShaahZmanisBaalHatanya()
         * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
         */
        public Instant getSofZmanBiurChametzBaalHatanya() {
                return getSofZmanBiurChametz(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * 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 #getChatzosHayomAsHalfDay() <em>chatzos</em> as half a
         *         day} for {@link AstronomicalCalculator calculators} that support it, based on {@link #isUseAstronomicalChatzos()}.
         * @see #getMinchaGedola(Instant, Instant)
         * @see #getShaahZmanisBaalHatanya()
         * @see #getMinchaKetanaBaalHatanya()
         * @return the {@code Instant} 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 when the sun does not rise,
         *         and one where it does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Instant getMinchaGedolaBaalHatanya() {
                return getMinchaGedola(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * 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>}.
         * 
         * @see #getMinchaKetana(Instant, Instant)
         * @see #getShaahZmanisBaalHatanya()
         * @see #getMinchaGedolaBaalHatanya()
         * @return the {@code Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Instant 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
         * <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> for more details on this calculation.
         * 
         * @see #getPlagHamincha(Instant, Instant)
         * @return the {@code Instant} 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 when the sun does not rise, and one where it
         *         does not set, a {@code null} will be returned. See detailed explanation on top of the
         *         {@link AstronomicalCalendar} documentation.
         */
        public Instant getPlagHaminchaBaalHatanya() {
                return getPlagHamincha(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
        }

        /**
         * A method that returns <em>tzais</em> (nightfall) when the sun is 6° below the western geometric horizon (90°) after {@link
         * #getSunset() sunset}.  This <em>tzais</em> / nightfall based on the opinion of the  <a href=
         * "https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>. This calculation is based on the position of the sun
         * about 24 minutes after {@link #getSeaLevelSunset() sunset} in Jerusalem <a href=
         * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which is 6°
         * below {@link AstronomicalCalendar#GEOMETRIC_ZENITH}. 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> that is based on {@link #getSunsetBaalHatanya() <em>shkiah amitis</em> as 1.583° below the
         * horizon} calculated around the equinox / equilux that computes 3.516 minutes after sunset. To this, 18 minutes of 3/4 of a
         * 24-minute mil and two minutes for <em>bain hashmashos</em> of Rav Yosi is added. This calculation computes the sun being
         * 5.83° below the horizon (very close to the slightly later {@link #getTzaisGeonim5Point95Degrees()} that was calculated based
         * on 4 fixed minutes) and it is rounded up to 6°.
         * 
         * @return The {@code Instant} 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} will be returned. See detailed
         *         explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getTzaisGeonim5Point95Degrees()
         * @see #getSunsetBaalHatanya()
         */
        public Instant getTzaisBaalHatanya() {
                return getSunsetOffsetByDegrees(ZENITH_6_DEGREES);
        }
        
        /**
         * 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_Gombiner">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°} and ends at {@link #getFixedLocalChatzosHayom() 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 Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos18Degrees()
         * @see #getFixedLocalChatzosHayom()
         * @see #getHalfDayBasedZman(Instant, Instant, double)
         */
        public Instant getSofZmanShmaMGA18DegreesToFixedLocalChatzos() {
                return getHalfDayBasedZman(getAlos18Degrees(), getFixedLocalChatzosHayom(), 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_Gombiner">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°} and ends at {@link #getFixedLocalChatzosHayom() 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 Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos16Point1Degrees()
         * @see #getFixedLocalChatzosHayom()
         * @see #getHalfDayBasedZman(Instant, Instant, double)
         */
        public Instant getSofZmanShmaMGA16Point1DegreesToFixedLocalChatzos() {
                return getHalfDayBasedZman(getAlos16Point1Degrees(), getFixedLocalChatzosHayom(), 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_Gombiner">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
         * #getAlos90Minutes() 90 minutes before sunrise} and ends at {@link #getFixedLocalChatzosHayom() 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 Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos90Minutes()
         * @see #getFixedLocalChatzosHayom()
         * @see #getHalfDayBasedZman(Instant, Instant, double)
         */
        public Instant getSofZmanShmaMGA90MinutesToFixedLocalChatzos() {
                return getHalfDayBasedZman(getAlos90Minutes(), getFixedLocalChatzosHayom(), 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_Gombiner">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
         * #getAlos72Minutes() 72 minutes before sunrise} and ends at {@link #getFixedLocalChatzosHayom()}. <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 Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getAlos72Minutes()
         * @see #getFixedLocalChatzosHayom()
         * @see #getHalfDayBasedZman(Instant, Instant, double)
         */
        public Instant getSofZmanShmaMGA72MinutesToFixedLocalChatzos() {
                return getHalfDayBasedZman(getAlos72Minutes(), getFixedLocalChatzosHayom(), 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()} and
         * ends at {@link #getFixedLocalChatzosHayom() 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 Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getSunset()
         * @see #getFixedLocalChatzosHayom()
         * @see #getHalfDayBasedZman(Instant, Instant, double)
         */
        public Instant getSofZmanShmaGRASunriseToFixedLocalChatzos() {
                return getHalfDayBasedZman(getSunriseBasedOnElevationSetting(), getFixedLocalChatzosHayom(), 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()} and ends at {@link #getFixedLocalChatzosHayom() 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 Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getSunset()
         * @see #getFixedLocalChatzosHayom()
         * @see #getHalfDayBasedZman(Instant, Instant, double)
         */
        public Instant getSofZmanTfilaGRASunriseToFixedLocalChatzos() {
                return getHalfDayBasedZman(getSunriseBasedOnElevationSetting(), getFixedLocalChatzosHayom(), 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> according to the<a href=
         * "https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> calculated as 30 minutes after {@link #getFixedLocalChatzosHayom() fixed
         * local chatzos}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getMinchaGedolaGRA()
         * @see #getFixedLocalChatzosHayom()
         * @see #getMinchaKetanaGRAFixedLocalChatzosToSunset
         */
        public Instant getMinchaGedolaGRAFixedLocalChatzos30Minutes() {
                return getTimeOffset(getFixedLocalChatzosHayom(), Duration.ofMinutes(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 #getFixedLocalChatzosHayom() fixed local chatzos}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getMinchaGedolaGRA()
         * @see #getFixedLocalChatzosHayom()
         * @see #getMinchaGedolaGRAFixedLocalChatzos30Minutes
         * @see #getHalfDayBasedZman(Instant, Instant, double)
         */
        public Instant getMinchaKetanaGRAFixedLocalChatzosToSunset() {
                return getHalfDayBasedZman(getFixedLocalChatzosHayom(), getSunsetBasedOnElevationSetting(), 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 #getFixedLocalChatzosHayom() fixed local chatzos}.
         * 
         * @return the {@code Instant} 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 when the sun does not rise, and one where it does not set, a
         *         {@code null} will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         * @see #getPlagHaminchaGRA()
         * @see #getFixedLocalChatzosHayom()
         * @see #getMinchaKetanaGRAFixedLocalChatzosToSunset
         * @see #getMinchaGedolaGRAFixedLocalChatzos30Minutes
         * @see #getHalfDayBasedZman(Instant, Instant, double)
         */
        public Instant getPlagHaminchaGRAFixedLocalChatzosToSunset() {
                return getHalfDayBasedZman(getFixedLocalChatzosHayom(), getSunsetBasedOnElevationSetting(), 4.75);
        }
        
        /**
         * Method to return <em>tzais</em> (dusk) calculated as 50 minutes after {@link #getSunset() sunset} or {@link
         * #getSeaLevelSunset() sea level sunset} (depending on the {@link #isUseElevation()} setting). 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 Instant} 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 when the sun does not rise, and one where it does not set, a {@code null} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant getTzais50Minutes() {
                return getTimeOffset(getSunsetBasedOnElevationSetting(), Duration.ofMinutes(50));
        }
        
        /**
         * A method for calculating <em>samuch lemincha ketana</em>, / near <em>mincha ketana</em> time that is half an hour before
         * {@link #getMinchaKetanaGRA()} or is 9 * <em>shaos zmaniyos</em> (solar hours) after the start of
         * the day, 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 #getShaahZmanisGRA()} after {@link #getSunrise()} or {@link
         * #getSunriseBasedOnElevationSetting() elevation adjusted sunrise} (depending on the {@link #isUseElevation()} setting). 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 #getSamuchLeMinchaKetana(Instant, Instant, boolean)
         * @see #isUseAstronomicalChatzosForOtherZmanim()
         * @return the {@code Instant} 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} will be
         *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant getSamuchLeMinchaKetanaGRA() {
                return getSamuchLeMinchaKetana(getSunriseBasedOnElevationSetting(), getSunsetBasedOnElevationSetting(), true);
        }
        
        /**
         * 
         * A method for calculating <em>samuch lemincha ketana</em>, / near <em>mincha ketana</em> time that is half an hour before
         * {@link #getMinchaKetanaGRA()} or is 9 * <em>shaos zmaniyos</em> (solar hours) after the start of the day, calculated based
         * on a day from   and ending  a day starting at {@link #getMinchaGedola16Point1Degrees() <em>alos</em> 16.1°} and ending
         * at {@link #getTzais72Minutes() <em>tzais</em> 16.1°}. 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°}. 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 #getSamuchLeMinchaKetana(Instant, Instant, boolean)
         * @see #getShaahZmanis16Point1Degrees()
         * @return the {@code Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant 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 #getMinchaKetanaGRA()} or is 9 * <em>shaos zmaniyos</em> (solar hours) after the start of the day, calculated based
         * on a day from   and ending  a day starting at {@link #getAlos72Minutes() <em>alos</em> 72 minutes} and ending at {@link
         * #getTzais72Minutes() <em>tzais</em> 72 minutes}. This is the time that eating or other activity can't begin prior to praying
         * <em>mincha</em>. The calculation used is 9 * {@link #getShaahZmanis72Minutes()} after {@link #getAlos72Minutes() <em>alos</em>
         * 72 minutes}. 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 #getSamuchLeMinchaKetana(Instant, Instant, boolean)
         * @see #getShaahZmanis72Minutes()
         * @return the {@code Instant} 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} will be returned.
         *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
         */
        public Instant getSamuchLeMinchaKetana72Minutes() {
                return getSamuchLeMinchaKetana(getAlos72Minutes(), getTzais72Minutes(), true);
        }
        
        /**
         * A method that returns sunset calculated as the time when the sun is directly due west (azimuth 270°) in <a href=
         * "https://en.wikipedia.org/wiki/Polar_regions_of_Earth">Polar regions</a> on days that there are no {@link
         * #getSunsetBasedOnElevationSetting() sunset}. If there is sunset that day, a {@code null} will be returned.
         * <p>In Polar regions (the <a href="https://en.wikipedia.org/wiki/Arctic">Arctic</a> or <a href=
         * "https://en.wikipedia.org/wiki/Antarctic">Antarctic</a> circles), there are days of no sunrise or sunset, and there are
         * <em>halachic</em> opinions that during these periods, sunset (the day-night boundary) is reached when the sun is directly due
         * west (azimuth 270°). Sunrise in this opinion is when the sun is directly due east (azimuth 90°) returned by {@link
         * #getPolarSunriseBenIshChai()}. This is the opinion of <a href="https://en.wikipedia.org/wiki/Joseph_Schwarz_(geographer)">Rabbi Yehosef
         * Schwarz</a> in his <a href="https://hebrewbooks.org/pdfpager.aspx?req=31703&pgnum=134">דברי יוסף – דרך מבוא השמש</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=159&pgnum=83">דברי יוסף – תשובות, שאלה ח׳</a>. This is brought down <em>lehalacha</em>
         * by The <a href="https://en.wikipedia.org/wiki/Yosef_Hayyim">Ben Ish Chai</a> in the <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=1401&pgnum=461">רב פעלים – חלק ב׳, סוד ישרים ס׳ ד׳</a>. This time is close to six hours
         * after {@link #getSunTransit() astronomical <em>chatzos hayom</em>}, but depending on the time of year and location in the
         *  Arctic / Antarctic, it can be up to 46 minutes before or after this time.
         * 
         * @return Sunset calculated as the time the sun is directly due west (azimuth 270°) in Polar regions on days that there is no
         *         sunset. If there is sunset that day, a {@code null} will be returned. While unlikely, it is theoretically possible
         *         for a {@code null} to be returned by the code even in Polar regions.
         * @see #getPolarSunriseBenIshChai()
         * @see #getTimeAtAzimuth90Or270(double)
         * @see com.kosherjava.zmanim.util.AstronomicalCalculator#getTimeAtAzimuth(LocalDate, GeoLocation, double)
         */
        public Instant getPolarSunsetBenIshChai() {
                if(getSunsetBasedOnElevationSetting() == null) {
                        return getTimeAtAzimuth90Or270(270);
                }
                return null;
        }
        
        /**
         * A method that returns sunrise calculated as the time when the sun is directly due east (azimuth 90°) in <a href=
         * "https://en.wikipedia.org/wiki/Polar_regions_of_Earth">Polar regions</a> on days that there are no {@link
         * #getSunriseBasedOnElevationSetting() sunrise}. If there is sunrise that day, a {@code null} will be returned.
         * <p>In Polar regions (the <a href="https://en.wikipedia.org/wiki/Arctic">Arctic</a> or <a href=
         * "https://en.wikipedia.org/wiki/Antarctic">Antarctic</a> circles), there are days of no sunrise or sunset, and there are
         * <em>halachic</em> opinions that during these periods, sunrise is reached when the sun is directly due east (azimuth 90°).
         * The day-night boundary (sunset) in these opinions is when the sun is directly due west (azimuth 270°) returned by
         * {@link #getPolarSunsetBenIshChai()}. This is the opinion of <a href=
         * "https://en.wikipedia.org/wiki/Joseph_Schwarz_(geographer)">Rabbi Yehosef Schwarz</a> in his <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=31703&pgnum=134">דברי יוסף – דרך מבוא השמש</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=159&pgnum=83">דברי יוסף – תשובות, שאלה ח׳</a>. This is brought down <em>lehalacha</em>
         * by The <a href="https://en.wikipedia.org/wiki/Yosef_Hayyim">Ben Ish Chai</a> in the <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=1401&pgnum=461">רב פעלים – חלק ב׳, סוד ישרים ס׳ ד׳</a>. This time is close to six hours
         * before {@link #getSunTransit() astronomical <em>chatzos hayom</em>}, but depending on the time of year and location in the
         *  Arctic / Antarctic, it can be up to 46 minutes before or after this time.
         * 
         * @return Sunrise calculated as the easternmost solar position (azimuth 90°) in Polar regions on days that there is no sunrise.
         *         If there is sunrise that day, a {@code null} will be returned. While unlikely, it is theoretically possible for a
         *         {@code null} to be returned by the code even in Polar regions.
         * @see #getPolarSunsetBenIshChai()
         * @see #getTimeAtAzimuth90Or270(double)
         * @see com.kosherjava.zmanim.util.AstronomicalCalculator#getTimeAtAzimuth(LocalDate, GeoLocation, double)
         */
        public Instant getPolarSunriseBenIshChai() {
                if(getSunriseBasedOnElevationSetting() == null) {
                        return getTimeAtAzimuth90Or270(90);
                }
                return null;
        }
        
        /**
         * A method that returns <em>Plag Hamincha</em> in <a href="https://en.wikipedia.org/wiki/Polar_regions_of_Earth">Polar
         * regions</a> on days that there are no {@link #getSunriseBasedOnElevationSetting() sunrise} and {@link
         * #getSunsetBasedOnElevationSetting() sunset}, calculated 10.75 <em>shaaos zmaniyos</em> of a day calculated starting at
         * {@link #getPolarSunriseBenIshChai()} and ending at {@link #getPolarSunsetBenIshChai()}. This is the opinion of <a href=
         * "https://en.wikipedia.org/wiki/Joseph_Schwarz_(geographer)">Rabbi Yehosef Schwarz</a> in his <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=31703&pgnum=134">דברי יוסף – דרך מבוא השמש</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=159&pgnum=83">דברי יוסף – תשובות, שאלה ח׳</a>. This is brought down <em>lehalacha</em>
         * by The <a href="https://en.wikipedia.org/wiki/Yosef_Hayyim">Ben Ish Chai</a> in the <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=1401&pgnum=461">רב פעלים – חלק ב׳, סוד ישרים ס׳ ד׳</a>.
         * 
         * @return <em>Plag Hamincha</em> according to the Ben Ish Chai in Polar regions on days that there is no sunrise or sunset.
         *         If there is sunrise or sunset that day, a {@code null} will be returned.
         * @see #getPolarSunriseBenIshChai()
         * @see #getPolarSunsetBenIshChai()
         * @see #getPlagHamincha(Instant, Instant, boolean)
         */
        public Instant getPolarPlagHaminchaBenIshChai() {
                return getPlagHamincha(getPolarSunriseBenIshChai(), getPolarSunsetBenIshChai(), true);
        }
        
        /**
         * In Polar regions during the period where the sun is above the horizon 24-hours a day, <a href=
         * "https://en.wikipedia.org/wiki/Moshe_Sternbuch">Rav Moshe Sternbuch</a> in <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=19963&st=&pgnum=316">מועדים וזמנים ח״ב ס׳ קנ״ה הע׳ א׳</a> (<span lang="he">ח״ד ס׳ ת״א
         * הע׳ א׳</span> in the new edition) and in תשובות והנהגות <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=20025&st=&pgnum=224">ח״א ס׳ שט״ו,</a> and <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=69067&st=&pgnum=135">ח״ה ס׳ פ״ד</a> ruled that during the Polar summer night-based
         * <em>mitzvos</em> are not applicable, and during the Polar winter, day-based mitzvos are not applicable. Despite this, the day
         * of the calendar week changes when the sun is at its lowest position (an instantaneous set and rise) at {@link
         * #getChatzosHalayla()} in the Polar summer and when it is at its highest position in the Polar winter that occurs at {@link
         * #getChatzosHayom()}. Rabbi Dovid Heber the author of the <a href="https://hebrewbooks.org/53000">שערי זמנים</a> who <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=53000&st=&pgnum=111">discusses the Moadim Uzmanim's opinion</a> clarified to me
         * that in the Polar winter this really only applies when there is no <em>alos hashachar</em>. The lack of <em>alos
         * hashachar</em> only occurs in Antarctica and in uninhabited extreme northern regions. This means almost every northern
         * inhabited location has an <em>alos hashachar</em> and "day" even on December 21st. This method considers <em>alos</em> to be
         * {@link #getAlos16Point1Degrees()}.
         * <p> It should be noted that in the <span lang="he">מועדים וזמנים</span> linked above that was published in 1961, Rav Moshe
         * Sternbuch mentions that [<span lang="he">ולתפלה, היום מתהלק, עד י״ב שעות שחרית,  ומאז מנחה, ומעריב מתפלל סמוך ללילה כרבי יהודה כנל״ד ...</span>].
         * This comment (in () in the original, and [] in the new edition published in 2023) was not brought down in the <span lang="he"
         * >תשובות והנהגות</span> vol. 1 that was published in 1977 nor in vol. 5. published in 2009. Since it is not clear to me if this
         * constitutes a retraction, the calculations for the start of <em>mincha</em> mentioned in the Moadim Uzmanim was omitted. This
         * is 12 hours after the start of the day (either {@link #getChatzosHalayla()}  in the Polar summer, or {@link #getChatzosHayom()}
         * in the Polar winter. {@link #getPolarPlagHaminchaTeshuvosVehanhagos()} was included and is the start of the time that
         * <em>maariv</em> can be recited (until the end of the Polar day).
         * was omitted.
         * 
         *  <em>plag hamincha</em>
         * were not implemented. For those* who want the zmanim, the end of <em>Shacharis</em> is essentially 12 hours after the start of the day (either {@link
         * #getChatzosHalayla()}  in the Polar summer, or {@link #getChatzosHayom()} in the Polar winter, while mincha will start at that
         * point and can in daven mincha until night (or plag).
         * <p>FIXME:
         * <ul>
         *   <li>Attempt to clarify the discrepancy.</li>
         *   <li>Research if an earlier alos such as 18° should be used</li>
         *   <li>Consider logic for day with EITHER an <em>alos</em> or a sunset</li>
         * </ul>
         * @return the time of the Jewish calendar transition to the next day in Polar regions according to Rav Moshe Sternbuch.
         * @see #getPolarPlagHaminchaTeshuvosVehanhagos()
         */
        public Instant getPolarStartOfDayTeshuvosVehanhagos() {
                if(getSunriseBasedOnElevationSetting() == null && getSunsetBasedOnElevationSetting() == null) {
                        Instant chatzosHayom = getChatzosHayom();
                        Instant chatzosHalayla = getChatzosHalayla();
                        double chatzosHayomSolarElevation = getAstronomicalCalculator().getSolarElevation(chatzosHayom, getGeoLocation());
                        double chatzosHalaylaSolarElevation = getAstronomicalCalculator().getSolarElevation(chatzosHalayla, getGeoLocation());
                        double sunriseElevation = getAstronomicalCalculator().getSolarRadius() + getAstronomicalCalculator().getRefraction();
                        if(chatzosHayomSolarElevation < (0 - sunriseElevation) && chatzosHalaylaSolarElevation < (0 - sunriseElevation) && // and the sun is always below the horizon
                                        getAlos16Point1Degrees() == null && getSunriseBasedOnElevationSetting() == null) { // Polar winter in either hemisphere no alos 16.1 or sunrise
                                return chatzosHayom; // the "sunrise" as the closest to the horizon
                        } else if(chatzosHayomSolarElevation > (0 - sunriseElevation) && chatzosHalaylaSolarElevation > (0 - sunriseElevation)) { // Polar summer when both are above the horizon
                                return chatzosHalayla;
                        }
                }
                return null;
        }
        
        /**
         * In Polar regions during the period where the sun is above the horizon 24-hours a day, <a href=
         * "https://en.wikipedia.org/wiki/Moshe_Sternbuch">Rav Moshe Sternbuch</a> in <a href=
         * "https://hebrewbooks.org/pdfpager.aspx?req=19963&st=&pgnum=316">מועדים וזמנים ח״ב ס׳ קנ״ה הע׳ א׳</a> (<span lang="he">ח״ד ס׳ ת״א
         * הע׳ א׳</span> in the new edition) mentions the concept of zmanim based on his {@link #getPolarStartOfDayTeshuvosVehanhagos()}.
         * This calculates {@link #getPlagHamincha(Instant, Instant, boolean)} as 10.75 <em>sha'os zmaniyos</em> starting 24 hours prior
         * to the current start/end of the current day. This will be very close to 2.5 clock hours before the start/end of the day.
         * @return <em>plag hamincha</em> as 2.5 hours prior to the start of the next day.
         * 
         * @see #getPolarStartOfDayTeshuvosVehanhagos() for more details on this opinion.
         * @see #getPlagHamincha(Instant, Instant, boolean)
         */
        public Instant getPolarPlagHaminchaTeshuvosVehanhagos() {
                Instant polarStartOfDay = getPolarStartOfDayTeshuvosVehanhagos();
                if(polarStartOfDay == null) {
                        return null;
                } else {
                        Instant yesterday = polarStartOfDay.minus(1, ChronoUnit.DAYS);
                        return getPlagHamincha(yesterday, polarStartOfDay, true);
                }
                
        }
        
        /**
         * @see java.lang.Object#equals(Object)
         */
        public boolean equals(Object object) {
                if (this == object) {
                        return true;
                }
                if (object == null || getClass() != object.getClass()) {
                        return false;
                }
                if (!super.equals(object)) {
                        return false;
                }
                ComprehensiveZmanimCalendar that = (ComprehensiveZmanimCalendar) object;
                return ateretTorahSunsetOffset == that.ateretTorahSunsetOffset;
        }

        /**
         * @see java.lang.Object#hashCode()
         */
        public int hashCode() {
                return 37 * super.hashCode() + Double.hashCode(ateretTorahSunsetOffset);
        }
}