Tefila Rules Added to KosherJava Zmanim Library

Kosel Picture 1932
Davening at the Kosel. This picture was taken by my grandfather Sidney (Nesanel) Siegfried on Aug 1, 1932 כ״ח תמוז תרצ״ב. This article was posted exactly 90 years to the day (Gregorian date) after the picture was taken.
The new TefilaRules class has been added to the KosherJava Zmanim Library. This will be included in the upcoming v2.4.0 release. The TefilaRules class was added in an effort to help zmanim calendar authors who sometimes require knowing if תחנון tachanun is recited on a specific day in order to set tefila times (such as mincha starting X minutes before shkiah, and a few minutes later if tachanun is not recited). It is also useful for siddur app creators. With many different minhagim (mostly chasidishe) about when tachanun is recited, the class currently supports 12 different options that can allow setting the rules for a majority of minhagim.
Yahrzeits such as 7 Adar, (Moshe Rabbeinu’s yahrzeit) or holidays celebrated by specific communities such as Purim Mezhbizh (Medzhybizh) celebrated on 11 Teves or Purim Saragossa celebrated on the 17th of Shevat (the Wikipedia date seems to be in error), are not (and likely never will be) supported by this class.
Other tefila related rules such as the existing Mashiv Haruach etc. rules were moved over from the JewishCalendar class to this new class where they have a more natural fit. The methods that were migrated over, were deprecated in the JewishCalendar class and will be removed in v3.0.0.

Key Methods in the TefilaRules Class

The following are the key methods in the new TefilaRules class.

Sample Code

TefilaRules tr = new TefilaRules();
JewishCalendar jCal = new JewishCalendar();
HebrewDateFormatter hdf = new HebrewDateFormatter();
hdf.setHebrewFormat(true); // Hebrew formatting
jCal.setJewishDate(5783, JewishDate.TISHREI, 1); // Rosh Hashana
System.out.println(hdf.format(jCal) + " - Is tachanun recited: " + tr.isTachanunRecitedShacharis(jCal));
jCal.setJewishDate(5729, JewishDate.SHEVAT, 21);
System.out.println(hdf.format(jCal) + " - is mashiv haruch recited: " + tr.isMashivHaruachRecited(jCal));
jCal.setJewishDate(5783, JewishDate.ADAR, 17);
System.out.println(hdf.format(jCal) + " - Is tachanun recited: " + tr.isTachanunRecitedShacharis(jCal));
tr.setTachanunRecitedWeekOfPurim(false); //default is true
System.out.println(hdf.format(jCal) + " - Is tachanun recited: " + tr.isTachanunRecitedShacharis(jCal));


א׳ תשרי תשפ״ג - Is tachanun recited: false
כ״א שבט תשכ״ט - is mashiv haruch recited: true
י״ז אדר תשפ״ג - Is tachanun recited: true
י״ז אדר תשפ״ג - Is tachanun recited: false

Zmanim API 2.3.0 Released

The KosherJava Zmanim API version 2.3.0 was released on Dec 7th, 2021 ג׳ טבת תשפ״ב in Maven and GitHub. While there have been numerous releases over the years, this is the first release-related post since the v1.3.0 release in 2013. If you have not updated since that time, you can expect some changes. The most significant changes (besides a lot of new functionality) are the simple to fix breaking changes listed below.

New in Version 2.3.0

The list of significant changes in this and previous releases can be seen in the KosherJava Zmanim API changelog.

Breaking Changes since v1.3

Rav Moshe Feinstein’s Zmanim Added to the KosherJava Zmanim API

Rav Moshe Feinstein is of the opinion that chatzos is at a fixed time all year round and is calculated based on the location’s longitude (in Lakewood, NJ it is at 11:56am / 12:56pm during DST). See Igros Moshe Orach Chaim vol 4 no. 20 who states

והנה החצות לילה באמת לא משתנה כלל מימים הארוכים דקיץ לימים הקצרים חזודף אף לא לרגע אחד, למה שכתבתי בספרי אגדות משה על או״ח בסימן כ״ד שחצות היום הוא לעולם שוה שהוא כשבא השמש לאמצע הדרום וזה שוה בכל השנה רק ששני חצאי היום אינם שוים רק איזה ימים בשנה ולפעמים חצי הראשון גדול ולפעמים חצי השני גדול עיי״ש, וכן קבלתי גם מאבי מורי זצללה׳׳ה.

See the Igros Moshe for more details. The Aruch Hashulchan in Orach Chaim 233 no. 14 also calculates chatzos at a fixed time all year.

ודע דחצות היום תמיד שוה בקיץ ובחורף כשיכה המורה שעות י״ב אז הוי חצות היום וכן בלילה שהרי השעות שנתוספו או נתקצרו חציים מקודם חצות וחציים מלאחר חצות וא׳׳כ ממילא דהחצות לעולם עומדת בשוה

Rav Moshe also bases other zmanim calculations on this fixed local chatzos. As opposed to calculating shaaos zmaniyos from beginning to the end of a day, Rav Moshe calculates a number of zmanim based on half of the day starting or ending at fixed local chatzos (see Igros Moshe Orach Chaim vol 1, no. 23).

ומש״כ ידידי שהלוח של הישיבה אינו מדוקדק, הנה הוא בדיוק גדול ונכתב על דעתי. והטעם דהחצות של היום שהוא כשבא השמש באמצע הדרום שוה לעולם, אבל שני חצאי היום אינם שוים רק איזה ימים בשנה ולפעמים חצי הראשון גדול ולפעמים חצי האחרון. ולכן בין לקולא בין לחומרא מסתבר שנחלקו שש שעות עד חצות ושש שעות מחצות עד הערב. ולכן מש״כ ידידי שהוא שבשתא וטעות לא דבר נכונה שהוא אמת גמור וליכא ע״ז שום קושיא.

These zmanim are used in Mesivta Tiferet Yerushalayim (MTJ), Yeshiva of Staten Island and Camp Yeshiva of Staten Island. Code to calculate these Rav Moshe zmanim is now part of the latest v2.3.0 release of the KosherJava Zmanim API.
The following new zmanim are now included in the API:

Sample Usage

For developers, here is sample code that calculates the new zmanim. This should allow many zmanim apps to add Rav Moshe Feinstein’s zmanim with very little effort.

String locationName = "145 E Broadway, New York, NY";
double latitude = 40.7138;
double longitude = -73.9913;
double elevation = 11;
TimeZone timeZone = TimeZone.getTimeZone("America/New_York");
GeoLocation location = new GeoLocation(locationName, latitude, longitude, elevation, timeZone);
ComplexZmanimCalendar czc = new ComplexZmanimCalendar(location);
czc.getCalendar().set(1986, Calendar.MARCH, 23); //Rav Moshe's petirah
System.out.println("Sof zman shma alos 18° to fixed local chatzos: " + czc.getSofZmanShmaMGA18DegreesToFixedLocalChatzos());
System.out.println("Sof zman shma alos 16.1° to fixed local chatzos: " + czc.getSofZmanShmaMGA16Point1DegreesToFixedLocalChatzos());
System.out.println("Sof zman shma alos 90 to fixed local chatzos: " + czc.getSofZmanShmaMGA90MinutesToFixedLocalChatzos());
System.out.println("Sof zman shma alos 72 to fixed local chatzos: " + czc.getSofZmanShmaMGA72MinutesToFixedLocalChatzos());
System.out.println("Sof zman shma sunrise to fixed local chatzos: " + czc.getSofZmanShmaGRASunriseToFixedLocalChatzos());
System.out.println("Sof zman tfila sunrise to fixed local chatzos: " + czc.getSofZmanTfilaGRASunriseToFixedLocalChatzos());
System.out.println("Mincha gedola 30 minutes after fixed local chatzos: " + czc.getMinchaGedolaGRAFixedLocalChatzos30Minutes());
System.out.println("Mincha katana fixed local chatzos to sunset: " + czc.getMinchaKetanaGRAFixedLocalChatzosToSunset());
System.out.println("Plag hamincha fixed local chatzos to sunset: " + czc.getPlagHaminchaGRAFixedLocalChatzosToSunset());
System.out.println("Tzais 50 minutes after sunset: " + czc.getTzais50());

Calculating other fixed local chatzos based zmanim not included in the library (and not necessarily endorsed by this shitta) are very simple with the generic getFixedLocalChatzosBasedZmanim(Date startOfHalfDay, Date endOfHalfDay, double hours) method built to simplify calculating these zmanim. Here are a few examples.

//4 hours into a day based on half the day from alos 18° to fixed local chatzos
System.out.println("Sof zman tfila 18° to fixed local chatzos: " + czc.getFixedLocalChatzosBasedZmanim(getAlos18Degrees(), getFixedLocalChatzos(), 4); 
//plag hamincha based on the second half of the day starting at fixed local chatzos and ending 50 minutes after sunset
System.out.println("Plag hamincha fixed local chatzos to tzais 50 minutes: " + czc.getFixedLocalChatzosBasedZmanim(getFixedLocalChatzos(), getTzais50(), 4.75); 

I would like to thank Avraham David Gelbfish who requested this addition and provided instructions on the proper calculations used by these yeshivos in calculating the zmanim.

Taanis Bechoros Added to the KosherJava Zmanim API

Years ago I posted the Calculating Erev Pesach Zmanim that discussed the addition of sof zman achilas chametz and sof zman biur chametz times to the API. Based on a request on the KosherJava project’s GitHub repository, a new isTaanisBechoros() method was added to the API. The Taanis Bechoros fast day usually occurs on Erev Pesach, but in years like this year (5781/תשפ״א – 2021) when Erev Pesach occurs on Shabbos, the fast is moved back to Thursday the 12th of Nissan. Erev Pesach occurs on Shabbos an average of once every 10 years. The frequency of such occurrences ranges from 3 to 20 years. It will next occur in the year 5785/תשפ״ה – 2025, followed 20 years later in the year 5805/תת״ה – 2045. The code is included in the new v2.2.0 release of the KosherJava zmanim library. The following code sample shows the basic usage of the new method.

JewishCalendar jd = new JewishCalendar();
HebrewDateFormatter hdf = new HebrewDateFormatter();
jd.setJewishDate(5781, JewishDate.NISSAN, 12);



Decimal Versus Sexagesimal Based Zmanim Location Errors

Decimal Analog Clock
Converting from one number system to another can be tricky. What time would 6:19 am/pm on this decimal based analog clock be on a regular duodecimal (12 based) clock? See the end of the article for the answer.

There are two different ways to reference latitude and longitude. One uses a sexagesimal (60 based) system of degrees indicated by a ° symbol, minutes indicated by a ' and seconds indicated by ". Think 60 minutes in an hour, 60 seconds in a minute and apply it to latitude numbers. The other system uses the more familiar decimal based format. For example The main BMG beis hamedrash is located at latitude 40.096, longitude -74.222 in degree/decimal. In degrees, minutes and seconds this would be latitude 40° 5′ 46″ N, longitude 74° 13′ 19″ W.

I was recently shown a zmanim calendar that seemed to be slightly inaccurate. Researching the issue showed that the intention was to generate the calendar for the location XX° 46′ N XX° 15′ W (latitude and longitude degrees are masked), but was mistakenly calculated for XX.46° -XX.15°. This confusion of the sexagesimal based system with the decimal based system is not uncommon. The discrepancy in sunrise and sunset in the calendar versus what it should have been was about 80 seconds in the summer. If someone were to confuse XX° 9′ with XX.9° (for both latitude and longitude) you have a much more significant relative error of 0.75°. The impact of this type of mistake is mostly caused by longitude, but latitude changes impact zmanim calculations as well. This 0.75° mistake can result in a zmanim discrepancy of up to five and a half minutes at the latitude of Lakewood, NJ. As confirmed by Dr. Noson Yanofsky, this scenario has the most extreme error, while 10′ confused with 0.10° has the least significant error of 0.066°.

An interesting variant of such a mistake is calculating a zman for a depression angle (how far the sun is below the horizon) that is based on degrees and minutes using degree/decimal. An example is mistakenly calculating tzais of 7° 5′ , or 7.083° as 7.5°. See Hazmanim Bahalacha vol II p. 520 footnote 21 for a case where this mistake happened. It should be noted that many are of the opinion that a depression angle of 7.5° is the proper time of tzais. This was used in the first ever known printed calendar calculated based on depression angles. It was published in תקכ״ו / 1766 by Raphael Levi Hannover. See Hazmanim Bahalacha p. 524 for a picture of the luach and a list of other calendars that calculate tzais as 7.5°.

To answer the question in the image caption above, the time in a regular 12 hour / duodecimal based clock would be 7:40. With 10 hours instead of 12, each decimal hour on this clock is 72 minutes of regular time. Therefore 6 hours = 432 minutes. Add ~19/50 decimal minutes that are equivalent to ~28/72 regular clock minutes and you end up with 460 minutes after noon/midnight, or about 7:40 🙂.