Trust through transparency

How the Panchangam engine works.

The calculation layer is deliberately separate from priestly judgment. The software computes astronomical reference values; Shri Venugopal Shastry confirms family-specific ritual decisions.

1. Drik astronomical basis

The engine follows an observation-based (Drik) approach. Apparent geocentric positions of the Sun and Moon, together with local solar rise and set times, are supplied by the open-source Astronomy Engine library. The site does not scrape or reproduce another priest website’s calendar output.

2. Sidereal reference

Nakshatra and Yoga are calculated in a Lahiri (Chitrapaksha) sidereal frame. The integration uses a J2000 Lahiri reference and standard precession terms to convert true ecliptic-of-date longitude into sidereal longitude. Tithi and Karana depend on the relative angular separation of Moon and Sun, so the common sidereal offset cancels.

3. The five limbs

Vara is the local weekday. Tithi divides the Moon–Sun elongation into 30 portions of 12 degrees. Nakshatra divides the Moon’s sidereal longitude into 27 portions of 13°20′. Yoga divides the sum of the sidereal longitudes of Sun and Moon into 27 equal portions. Karana is half a Tithi, with the traditional repeating and fixed Karana sequence.

4. Sunrise, sunset and daily kalam

Sunrise and sunset are calculated for the selected coordinates. Rahu Kalam, Yamagandam and Gulika Kalam are derived by dividing the sunrise-to-sunset interval into eight equal parts and assigning the traditional weekday segment. Abhijit is shown as a midday reference interval and Brahma Muhurta as the traditional pre-sunrise reference used by this interface.

5. Transition times

For Tithi, Nakshatra, Yoga and Karana, the browser searches forward from sunrise for the next change and numerically narrows the transition time. Because published Panchangams can use different ephemerides, ayanamsha realizations, sunrise conventions and rounding, small timing differences are normal.

6. Observances and festivals

The current engine can identify preliminary recurring candidates such as Ekadashi, Pradosham, Purnima, Amavasya and Sankashti from the Tithi at sunrise. This is intentionally not treated as a complete festival engine. Many festivals depend on whether a Tithi prevails at sunrise, moonrise, midday or another tradition-specific reference. Named festivals should be added only through a separately reviewed rules/data layer.

7. What the engine does not do

It does not approve a wedding or Griha Pravesham Muhurtham; perform horoscope matching; evaluate Tara Bala, Chandra Bala, Lagna or every ceremony-specific rule; or override a family’s sampradaya. It is a transparent astronomical reference tool, not an automated priest.

For an important samskara, the final question is not merely “what does the calculator say?” but “what is appropriate for this family, this ceremony, this place and this tradition?”

8. Review and correction policy

Before public launch, the engine should be compared across a representative date set against an independently respected Drik Panchangam and reviewed by Shri Venugopal Shastry or another qualified Panchangam scholar. Any material discrepancy should be documented and corrected rather than hidden.