Hi, thanks for using the Hebcal Yahrzeit + Anniversary calendar.

Hebcal uses the yahrzeit algorithm defined in Calendrical Calculations by Edward M. Reingold and Nachum Dershowitz.

The customary anniversary date of a death is more complicated and depends also on the character of the year in which the first anniversary occurs. There are several cases:

• If the date of death is Marcheshvan 30, the anniversary in general depends on the first anniversary; if that first anniversary was not Marcheshvan 30, use the day before Kislev 1.
• If the date of death is Kislev 30, the anniversary in general again depends on the first anniversary — if that was not Kislev 30, use the day before Tevet 1.
• If the date of death is Adar II, the anniversary is the same day in the last month of the Hebrew year (Adar or Adar II).
• If the date of death is Adar I 30, the anniversary in a Hebrew year that is not a leap year (in which Adar only has 29 days) is the last day in Shevat.
• In all other cases, use the normal (that is, same month number) anniversary of the date of death.

[Calendrical Calculations p. 113]

Now, using the date you mentioned above:

Sat, 20 February 1988 = 2nd of Adar, 5748   ב׳ בַּאֲדָר תשמ״ח

Since 5748 was not a leap year, there was only one Adar that year. This means that the death occurred in 12th month of the Hebrew year.

Suppose one wishes to observe the yahrzeit in Hebrew year 5782. Since 5782 is a leap year and none of the other rules applies, we use the same month number as the date of death. In a leap year the 12th month is Adar I, so the yahrzeit is observed on 2nd of Adar I, 5782 (Thu, 3 Feb 2022).

More information here:

https://www.hebcal.com/home/54/anniversaries-adar-cheshvan-kislev

Thanks for the bug report!

We have fixed the error and the page is working correctly once again.

Our sincere apologies for the inconvenience.

It happens pretty rarely.

12/21/1831 17th of Tevet, 5592

12/21/1869 17th of Tevet, 5630

12/21/1888 17th of Tevet, 5649

12/21/1937 17th of Tevet, 5698

12/21/1945 17th of Tevet, 5706

12/21/1956 17th of Tevet, 5717

12/21/1975 17th of Tevet, 5736

12/21/2021 17th of Tevet, 5782

12/21/2040 17th of Tevet, 5801

12/21/2059 17th of Tevet, 5820

12/21/2078 17th of Tevet, 5839

12/21/2108 17th of Tevet, 5869

12/21/2127 17th of Tevet, 5888

12/21/2173 17th of Tevet, 5934

12/21/2184 17th of Tevet, 5945

12/21/2192 17th of Tevet, 5953

12/21/2241 17th of Tevet, 6002

12/21/2260 17th of Tevet, 6021

12/21/2279 17th of Tevet, 6040

12/21/2298 17th of Tevet, 6059

Hi, we were able to make an update to better display both Israel and Diaspora events using the date converter page.

For example:

https://www.hebcal.com/converter?gd=25&gm=4&gy=2022&g2h=1

When the parsha haShavua differs between the two locations, you'll see this noted with "in Israel" or "in the Diaspora" after the name of the event

Hi, thanks for using Hebcal.

Hebcal offers perpetual calendars for any date in Gregorian year 0001 through 9999. If you generate a calendar using our custom calendar page at https://www.hebcal.com/hebcal you can enter the year you choose.

Calendar feeds using iCalendar will vary in length based on the options specified.

If you're using the Hebcal Jewish calendar REST then you can specify specific dates using the start and end parameters.

Hello again, we've been alerted to a recent revision to the Triennial aliyot which explains the discrepancy you see between what Hebcal had published and Rabbi Miles B. Cohen's luach.

In November 2020, the CJLS modified the triennial cycle for some combined parshiyot to change the reading for year 3 to be the third section of the parashah.

Modification of the Triennial Cycle Readings for Combined Parashot in Certain Years, Rabbi Miles B. Cohen

We have implemented the revised aliyah scheme according to the CJLS and updated our web page earlier today to match

https://www.hebcal.com/sedrot/achrei-mot-20220430

Triennial year 3

1: 17:1-7 · 7 p’sukim

2: 17:8-12 · 5 p’sukim

3: 17:13-16 · 4 p’sukim

4: 18:1-5 · 5 p’sukim

5: 18:6-21 · 16 p’sukim

6: 18:22-25 · 4 p’sukim 

7: 18:26-30 · 5 p’sukim 

maf: 18:26-30 · 5 p’sukim

Shabbat Shalom!

Hi, we're sorry to hear you are having trouble finding Shabbat yom tov and fast day times on Hebcal.

If you enter your location on our Custom Calendar page you will get candle-lighting times for Shabbat and holidays, and also fast start/end times.

If you're having trouble seeing these times, can you send a URL and/or a screenshot so we can assist in debugging further?

Hi, thanks for using Hebcal's Zmanim API!

To avoid excessive CPU usage and ensure quick response times, we limit the total range for Zmanim to be 45 days. If the "end" parameter is more than 45 days after the "start" parameter, is reset to 45 days.

Similarly, if you want to represent numbers using gematriya, you can avoid using the REST API completely and instead use a simple gematriya function in the programming language of your choice.

Here's the implementation that Hebcal uses. If you don't use JavaScript, you'll see it's extremely straightforward to port to another programming language.

https://github.com/hebcal/hebcal-es6/blob/main/src/gematriya.js

For example, here's a port to Swift

https://github.com/hebcal/hebcal-swift/blob/main/Sources/Hebcal/hebnum.swift