Sunrise Calculation
The NOAA has a page describing the sunrise calculation here (pdf).
Jewish Calendar References
The algorithms for hebcal were taken from Emacs 19's calendar routines by Edward M. Reingold and Nachum Dershowitz. Their program is extremely clear and provides many instructive examples of fine calendar code in emacs-LISP.
Books
- Understanding the Jewish Calendar
- by Rabbi Nathan Bushwick. A well written treatment of the Jewish Calendar. Good bibliography.
- Encyclopedia Judaica
- Always the right place to start. Check out their entry on Calendar
- Calendrical Calculations
- Reingold and Dershowitz's own text. A keeper.
Other Good References
- Hebrew Calendar Science and Myths
- Fun stuff, page with neat-o facts about the arithmetic of the Jewish Calendar and its consequences.