Can you recommend any books on the Hebrew Calendar or Jewish Holidays?

Posted by & filed under General.

For a good reference book on the major Jewish Holidays, I’d suggest Michael Strassfeld’s The Jewish Holidays: A Guide & Commentary. Rabbi Nathan Bushwick’s Understanding the Jewish Calendar explains some of the mathematical and scientific underpinnings of the calendar. For a comprehensive look at 25 different calendar systems (including Hebrew, Gregorian, Julian, Mayan and Hindu),… Read more »

Can I download a copy of the program for my computer?

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Hebcal for UNIX is a free program and is available for download at This is the same engine that powers the website. The downloadable program has a text (command-line) interface, not a fancy graphical one. Kaluach is an unrelated program available at The author requests donations, but does not have a set… Read more »

When does Shabbat begin?

Posted by & filed under Candle lighting.

Shabbat begins 18 minutes before sundown on Friday night. In Jerusalem, Shabbat begins 40 minutes before sundown. According to the United States Naval Observatory, Sunrise or sunset is defined to occur when the geometric zenith distance of center of the Sun is 90.8333 degrees. That is, the center of the Sun is geometrically 50 arcminutes below… Read more »

What is Havdalah (or, When does Shabbat end)?

Posted by & filed under Candle lighting, Observance.

Shabbat ends after sundown on Saturday night when there are three stars visible. Depending on latitude and longitude, this is usually between 42 and 72 minutes after sundown. According to Wikipedia, There are three widely observed practices, all of which have support in the halachic literature: Appearance of three medium-sized stars in the sky (sun… Read more »

If I use 72 minutes for Havdalah, why are Havdalah times ~90 minutes later than the previous day’s candle-lighting time?

Posted by & filed under Candle lighting.

Shabbat begins 18 minutes before sundown on Friday night. Havdalah is 72 minutes after sundown on Saturday night. So in a given week, Havdalah time is typically 90 minutes after the previous day’s candle-lighting time (18 + 72 = 90). Sometimes there’s an extra minute or two difference, and that’s due to sunset actually differing… Read more »

How accurate are candle lighting times?

Posted by & filed under Candle lighting.

Hebcal computes sunset based on an algorithm provided by the U.S. Naval Observatory (USNO). The USNO claims accuracy within 2 minutes except at extreme northern or southern latitudes. Comparison to local NWS charts for sunrise and sunset (which are cheap and easy to come by) shows that with the double precision calculations, the charts produced by… Read more »

How are candle lighting times determined from my zip code?

Posted by & filed under Candle lighting.

Since candle lighting times are determined from latitude and longitude, a process called geocoding is used to determine the geographic position of a zip code. Our zip code database comes from the 1999 ZIP Code file from the U.S. Census Bureau’s Gazetteer project. The Gazetteer data from 1999 is much more complete than their data from… Read more »

What cities outside of the USA are available?

Posted by & filed under Candle lighting.

Candle-lighting and Havdalah times are available for the following 54 cities: Ashdod (31d48′ N lat, 34d38′ E long, GMT +2:00, israel) Atlanta (33d45′ N lat, 84d23′ W long, GMT -5:00, usa) Austin (30d16′ N lat, 97d45′ W long, GMT -6:00, usa) Baghdad (33d14′ N lat, 44d22′ E long, GMT +3:00, eu) Beer Sheva (31d15′ N… Read more »

Lotus Notes 6 Jewish holidays download

Posted by & filed under Download - General.

Lotus Notes is not supported by These instructions were provided by user Bruce Kahn. Your mileage may vary. Start Notes Create a new mail memo Attach the iCalendar file you just downloaded and save the memo as Draft Open the Draft memo up and right click on the attachment From the popup select… Read more »

Palm Desktop 4.1.4 Jewish holidays download

Posted by & filed under Download - Palm.

Follow these instructions to add a Hebcal Jewish holiday calendar 5-year feed to the old version of Palm Desktop 4.1.4. Note that these instructions do not work for the newer Palm Desktop 6.2. If you are using the newer version, please instead use our . First, you’ll need to download a Palm Date Book Archive… Read more »