In CalJ, the Zmanim for Alot haShachar (עלות השחר) and Earliest Tefilin are calculated as follows:
- Alot haShachar = 72 halachical minutes (seasonal) before the Netz (הנץ החמה)
- Earliest Tefilin = 6 seasonal minutes after Alot haShachar
The sunrise itself (Netz) is when the Sun is -0,8333 degrees below the horizon (first visible rays).
Sholom Aleichem,
I had been using your app on iPhone for a while now- it’s is becoming better every time! I have a question, how do you calculated earliest time of Shma/Tfilin(not R. Ovadia’s opinion)?
Thank you in advance and Shabbat shalom.
Alex
Dear Alex,
Thank you for using my app.
In the opinion of Rav Meir Posen שליט”א, the earliest time for Tefilin is when the Sun is 11 degrees below the horizon line.
I don’t know what I’d do without this app. GISHMACH! Tizku l mitzva. Chazaq u Baruch.
Thank you very much!