Method

Every time on Amrutkaal is calculated from mathematics — no assumptions or memorized tables. Here's how.

Computational foundation

We use Swiss Ephemeris (pyswisseph) — Astrodienst's astronomical library based on NASA JPL's DE431 planetary equations. It is the same engine used to compute India's official Rashtriya Panchang.

Ayanamsa

We use Lahiri ayanamsa — the Indian government's official standard since 1955. It corrects for the difference between sayana (tropical) and nirayana (sidereal) calendars. Other ayanamsas (Raman, KP) will be available as options in Phase 2.

Sunrise & Sunset

We compute the geometric horizon crossing of the sun's upper limb with standard atmospheric refraction. This is the same rule NOAA uses for civil sunrise. Accuracy: within ±30 seconds.

Tithi, Nakshatra, Yoga, Karana

These are four of the five "limbs" of panchang. Each is derived from the sidereal longitudes of the moon and sun:

• Tithi = (moon longitude − sun longitude) / 12° — 30 tithis per lunar month
• Nakshatra = moon longitude / 13°20′ — 27 nakshatras of the zodiac
• Yoga = (moon + sun longitude) / 13°20′ — 27 yogas
• Karana = (moon − sun) / 6° — 11 karanas, 4 fixed + 7 moveable

Transition times (when tithi/nakshatra/yoga ends and the next begins) are found by bisection search to ±1 second precision.

Rahu Kaal, Abhijit, and other muhurat windows

The day (sunrise to sunset) is divided into eight equal parts. Rahu Kaal, Gulika Kaal, and Yamaganda fall in a specific part each weekday — this is traditional rule, not astrology. Abhijit Muhurat is the 8th of 15 muhurtas of the day, centered on solar noon. Brahma Muhurat is the last 48 minutes before sunrise.

Festival dates

Festival dates are hand-curated and cross-verified against Drik Panchang's published calendar. Dates listed for 2026 through 2030. After Phase 2, these will be auto-verified via the festival data crawler.

Accuracy claim

Sunrise / sunset: ±30 seconds. Tithi / nakshatra / yoga transitions: ±1 minute. Validated against 50 sample dates from Drik Panchang. If you find a value off by more than this, please email hello@amrutkaal.com with the city, date, value we showed, and the reference.

What we don't do

• We don't predict your future.
• We don't give medical, legal, or financial advice.
• We don't generate horoscopes.
• We don't use AI to compute times — only for language (descriptions, translations).

More questions? Please write to hello@amrutkaal.com.