How nakshatra is calculated

The Moon’s position in the sidereal zodiac determines its nakshatra: one of 27 equal divisions, each spanning 13 degrees 20 minutes.

The nakshatra on a daily page describes the part of the zodiac occupied by the Moon at local sunrise. The accompanying time shows when the Moon moves into the next nakshatra.

Nakshatra and pada

Each nakshatra has four padas, or quarters, of 3 degrees 20 minutes each. A birth nakshatra and pada are calculated for the time of birth. They are different from the daily reading shown for today's sunrise.

Why ayanamsha matters

Ayanamsha is the offset between the tropical and sidereal zodiacs. It is applied to the Moon's longitude before identifying the nakshatra. Different ayanamsha conventions can therefore give different boundary times.

The method used here

This site uses the Lahiri ayanamsha, the one most Indian panchangams use.