How this is calculated

Sunrise and sunset are for the centre of the sun’s disc without refraction, as in the app. Each tithi, nakshatra and yoga ends at the exact moment the moon or sun crosses its boundary, so a day can have two. Rahu Kaal, Yamaganda and Gulika divide daylight into eight parts by weekday; Abhijit is the eighth of fifteen daytime muhurtas and Brahma Muhurat the fourteenth of the night. Amrit Kalam and Varjyam fall at fixed points within each nakshatra, and Bhadra is the Vishti karana. The moon is drawn as it is lit at sunrise. Months are amanta.

Place names and time zones from GeoNames (CC BY 4.0).