Why One Panchang Cannot Serve Every Indian City

Indian Standard Time is the mean time of the meridian near Mirzapur. The Sun does not cross every city's meridian at 12:00 on that clock. East-coast mornings arrive earlier in solar terms than west-coast mornings, so the Moon's tithi, which is sliding all the time, can be caught at sunrise in Ranchi and already finished at sunrise in Mumbai. Nakshatra, yoga, and karana slip the same way. Weekday is stabler, because it changes at sunrise too but only once in twenty-four hours, and a close tithi is the usual casualty. This is why a national app with one set of limbs misleads a wedding party that travels. The muhurta has to be rebuilt for the city of the rite.

A kundli uses the zone offset in minutes before the Julian day, then the local horizon for the lagna. For an Indian birth the offset does not jump for daylight saving, which removes one foreign error and leaves the city error. Two births at the same clock time in Kolkata and Mumbai are the same Universal Time instant and not the same horizon, so the lagnas can differ. The Moon's nakshatra is shared more often, because the Moon does not care about the local horizon, but a nakshatra boundary can still fall between the two clock readings if someone converts wrongly. Jyothish SI geocodes the city for that reason. A state name is not a city. The panchang and the kundli both refuse it.

Pick the city. Read tithi, nakshatra, yoga, and karana at that sunrise. Avoid Bhadra if the act is a wedding or a foundation, and prefer a dhruva nakshatra if the act should last. Do not import a birth-chart raja yoga into the day's yoga name. Do not treat the panchang as a prediction of the native's mahadasha. The dasha is natal, fixed from the Moon's birth star, 120 years in sum. The panchang is today's sky at one sunrise. Keeping those jobs apart is the whole skill of the Hindu calendar in practice.