The Zmanim library is an API for a specialized calendar that can calculate different astronomical times including sunrise and sunset and Jewish zmanim or religious times for prayers and other Jewish religious dutuies. These classes extend GregorianCalendar and can therefore use the standard Calendar functionality to change dates etc. For non religious astronomical / solar calculations use the AstronomicalCalendar. The ZmanimCalendar contains the most common zmanim or religious time calculations. For a much more extensive list of zmanim use the ComplexZmanimCalendar. This class contains the main functionality of the Zmanim library.

Disclaimer:

While I did my best to get accurate results please do not rely on these zmanim for halacha lemaaseh