Posted by & filed under General. was primarily authored using hand-coded HTML5, PHP and Perl in Sublime Text 3 and Aquamacs.

Our minimalist, responsive design is provided by the Bootstrap framework.

The website runs on Apache HTTP Server on Ubuntu Linux. We use the Varnish HTTP accelerator and Pound for HTTPS (TSL/SSL) termination. We primarily use DigitalOcean and Netkine for hosting, with occasional use of Amazon Web Services (primarily SES for weekly emails and S3 for backups). Static pages are generated with GNU make and scheduled by Vixie Cron.

Our Help pages and news archives are powered by WordPress.

We use MySQL to store our email subscriber database, and SQLite for latitude/longitude location databases (GeoNames and USA ZIP codes).

Typefaces primarily uses Helvetica Neue for body and headers. Helvetica Neue is the default font for Bootstrap

Hebrew body and headline text is Alef Hebrew.

The Hebcal logo uses SBL Hebrew and Merriweather.

Posted by & filed under Observance.

Why does Pesach begin on the 15th of Nisan when Numbers 28:16 says “And in the first month, on the fourteenth day of the month, is the LORD’S passover”?

Special thanks to Rabbi George Schlesinger for this guest post.

First of all, it’s helpful to know and understand the Hebrew and to know that in ancient days there were two sacrifices i.e. two holidays that were conjoined into one in later days. There was the Pascal sacrifice/Pascal holiday which was known as the “Pesach” or “passover.” This was an agricultural holiday celebrating springtime and the new lambs of the flock and it apparently preceded the Exodus from Egypt by many, many years. That sacrifice/holiday was on the 14th of Nisan. And it’s the term that in later days came to be used in Judaism for what was in ancient times a separate sacrifice/holiday celebrated a day later…the 15th of Nisan and the start of a 7 day festival during which matza was eaten. The holiday celebrating the Exodus is (in the Bible) usually called Chag HaMatzot or Festival of Matzah. So a more precise translation of verses 16 and 17 would read:

וּבַחֹ֣דֶשׁ הָרִאשׁ֗וֹן בְּאַרְבָּעָ֥ה עָשָׂ֛ר י֖וֹם לַחֹ֑דֶשׁ פֶּ֖סַח לַיהוָֽה׃

16) In the first month, on the fourteenth day of the month, there shall be a passover (pesach) sacrifice to the Lord

וּבַחֲמִשָּׁ֨ה עָשָׂ֥ר י֛וֹם לַחֹ֥דֶשׁ הַזֶּ֖ה חָ֑ג שִׁבְעַ֣ת יָמִ֔ים מַצּ֖וֹת יֵאָכֵֽל׃

17) and on the fifteenth day of that month a festival (chag). Unleavened bread shall be eaten for seven days.

To add just a little, I quote from the Jewish Publication Society’s commentary on the Book of Numbers on page 243:

“The day of the paschal offering and the seven-day Festival of Unleavened Bread are discrete holidays. Yet the fact that the paschal offering is mentioned even though it is a private sacrifice (see Exodus 12:1-11) –– and hence no description is given –– indicates that the two festivals are already fused.”

In later centuries, the two sacrifices were both made on the 14th of Nisan. The “pesach”/paschal offering earlier in the day than the offering for the Chag HaMatzot since that was the lamb that was to be eaten at the Seder commemorating the Exodus and it had to be slaughtered and roasted prior to sundown of the 15th so that it could be consumed during the Seder.


Posted by & filed under News.

Chile will not change clocks in April 2015 or thereafter; its new standard time will be its old daylight saving time. We have updated Hebcal’s candle-lighting times engine to reflect the change.

If you downloaded or printed candle-lighting times for Santiago or any other city in Chile, be sure to re-download sometime before Pesach.

Posted by & filed under Observance.

In general, Jewish Holidays begin the evening before the date specified. This is because the Jewish day actually begins at sundown on the previous night. Sometimes, for clarity, the Erev holiday is also included to indicate that the holiday begins the evening before.

For example, in the April 2015 calendar below, Erev Pesach is listed as April 3rd and the first day of Pesach is listed as April 4th. This means that the holiday of Pesach begins on the evening on April 3rd.

And, Rosh Chodesh Iyyar is listed on April 19. This means that Rosh Chodesh begins on the evening of April 18, even though the Erev is not explicitly mentioned on the calendar.

April 2015

Sun Mon Tue Wed Thu Fri Sat
1 2 3









12 13 14 15 16

17 18


21 22


24 25
26 27 28 29 30

Minor fasts (Tzom GedaliahAsara B’TevetTa’anit EstherTa’anit Bechorot, and Tzom Tammuz) begin at dawn. Major fasts (Yom Kippur and Tish’a B’Av) begin the evening before.

Posted by & filed under Developers, APIs, RSS Feeds, Source Code.

To display a Jewish calendar on your website, you can use event data from and the open source JavaScript event calendar from

First, you’ll want to start by including the CSS and JS in your header, per the FullCalendar Basic Usage.

Then, for the events configuration, use a url that references our Jewish calendar REST API, but change cfg=json to cfg=fc.

You won’t need to specify a year=YYYY parameter, as the script automatically sends start=YYYY-MM-DD and end=YYYY-MM-DD parameters for you.

For best performance, be sure to use cache: true.

Here’s the FullCalendar invocation:

If you’d like to include candle-lighting times for Shabbat and holidays, be sure to adjust the url parameter to include c=on and one of the location fields (such as geonameid=3448439 for São Paulo, Brazil).

We recommend some specific styles to make the page look prettier:

Here’s a complete example that uses the aforementioned JS + CSS, and also includes the necessary stuff to load and dependencies via CDN: