Understanding the Available Zmanim Methods
The Help Book distinguishes generic methods based on widely established practice from community-specific methods associated with particular rabbinic and communal traditions.
Generic methods
The generic methods reflect the calculation systems commonly used in Jewish calendars, newspapers, synagogue schedules, and other community publications. They are based on two widely recognized approaches:
- GRA, based on the daytime calculation associated with the Vilna Gaon.
- Magen Avraham, often abbreviated MA, which uses an extended halachic day for certain morning deadlines.
Kaluach Mac provides GRA and Magen Avraham versions for Israel and for the diaspora. The underlying concepts remain the same, but practical implementation may vary with regional convention and established community practice.
| Region | GRA | Magen Avraham |
|---|---|---|
| Israel | GRA for Israel | MA for Israel |
| Diaspora | GRA for the diaspora | MA for the diaspora |
These options represent the familiar zmanim commonly found in calendars and synagogue schedules. Publications may still differ slightly because of astronomical data, elevation settings, rounding rules, or local customs.
Community-specific zmanim shitot
The app includes methods associated with Rav Ovadia Yosef, Rav Mordechai Eliyahu, Rav Meir Mazuz and Kisei Rachamim, and Rav Nissim Ezra Kaduri Chazan and Maaseh Nissim. These are not merely renamed generic options. Each preserves a particular halachic and communal tradition.
The app also includes a bundled Chabad profile based on Chabad.org’s published method. The linked guides explain the background and calculations of each method.