Jewish Time-Zemanim Definitions

• Alos HaShachar = 72 Minutes before Netz
• Alos HaShachar = When the center of the sun is at a 16.113 degrees depression angle below the horizon
• Misheyakir = When the center of the sun is at an 11 degrees depression angle below the horizon
• Netz HaChamah (Sunrise) = When the center of the sun is at a 0.833 degrees depression angle below the horizon
• Sof Zman Krias Shema = Gr"a; 1/4 of the day from Netz to Shkiah
• Sof Zman Krias Shema = Magen Avraham; 1/4 of the day from Alos 72 to Tzais 72
• Sof Zman Tefillah = Gr"a; 1/3 of the day from Netz to Shkiah
• Sof Zman Tefillah = Magen Avraham; 1/3 of the day from Alos 72 to Tzais 72
• Chatzos = 1/2 of the day from Netz to Shkiah is the true high noon and Shkiah to Netz is the true midnight.
• Minchah Gedolah = Either 30 minutes or a half hour Shaah Zmaniyos after Chatzos, whikever is later
• Minchah Ketanah = 9.5/12 of the day from Netz to Shkiah
• Plag HaMinchah = 10.75/12 of the day from Netz to Shkiah
• Candle Lighting = 18 minutes before Shkiah, in Jerusalem it's 40 minutes before Shkiah.
• Shkias Hachamah (Sunset) = When the center of the sun is at a 0.833 degrees depression angle below the horizon
• Tzais HaKochavim = When the center of the sun is at a 9.25 degrees depression angle below the horizon
• Tzais HaKochavim = 72 Minutes after Shkiah