How every date and time here is computed

The Sun, the Moon and the planets

The planets come from IMCCE's VSOP87D series and the Moon from the full tables of Meeus's Astronomical Algorithms, with nutation, aberration and light time applied. The planets are held against NASA JPL's DE421 ephemeris to within a third of an arc-minute between 1950 and 2050, and the kundli's ephemeris to under an arc-second for the planets.

The sidereal zodiac

Sidereal positions use the Lahiri (Chitrapaksha) ayanamsa, the Government of India's standard, and Rahu is the mean node: the one that reproduces the published Indian transits.

Your town, your clock

Sunrise is the moment the upper edge of the Sun touches a flat horizon at the town's own latitude and longitude, with the usual refraction. Every time is printed on the town's own clock, from its time zone and its own daylight-saving dates, rounded to the minute as a printed panchang rounds it.

A festival's date

Each day is fixed by its own rule, as the tradition gives it: the tithi at sunrise, at midday, in pradosh or at moonrise; the month in the tradition's own reckoning, amanta or purnimanta or solar. The rules are written as data, each with its source, and the year they produce is measured against the published almanacs of every region.

The kundli in your browser

The free kundli runs in the browser, so a birth never leaves the device. It reads the app's own ephemeris through Chebyshev series fitted to it, and is tested against four hundred charts the app's engine cast in full: every graha within a thousandth of an arc-second, every nakshatra, pada, navamsa, dignity and dasha the same.

When another panchang says otherwise

By a minute or two: each publisher chooses its own rule for the horizon, for refraction and for the exact point it calls a city. By a day: usually a regional rule, and the page says so. Where Kalava differs from a published date on purpose, the reason is recorded, and the list is public.

The accuracy study