How We Check Our Numbers

Every chart, panchang and festival date on this site comes from one calculation engine. This page shows how close that engine comes to the references astronomers use, measured on 31 October 2026, with the files to check it yourself.

In short

To put an arc-second in scale: it is 1/3,600 of a degree. A nakshatra pada is 12,000 arc-seconds wide, and the Moon moves about half an arc-second every second. The US Naval Observatory publishes its times to the whole minute, so up to 30 seconds of the difference with it is their rounding, not a disagreement.

“An independent calculation” means the same quantity worked out by a separate, widely used astronomy program, not by our code, with the same conventions.

What the engine uses

• Planet positions: NASA JPL DE440, the planetary ephemeris of NASA’s Jet Propulsion Laboratory. We calculated yearly tables from it once, for 1899 to 2075, and the site reads them in your browser. Between the stored points the position is filled in by interpolation. No outside service is called when you make a chart, so the kundali and every calculator give the same numbers.
• Ayanamsa: Lahiri (Chitrapaksha), the value used by the Government of India’s Rashtriya Panchang.
• Rahu and Ketu: the mean lunar node.
• Places and time zones: the place you pick gives the latitude, longitude and time zone, from the IANA time zone database.

The sources, texts and limits behind the written pages are on the Method page.

Planet positions against NASA JPL Horizons

Horizons is NASA’s own online service for the positions of the Sun, Moon and planets. For 20 moments from 1 January 1900 to 15 December 2075, including war-time births in 1942 to 1945 and 15 August 1947, we compared our tropical longitude with the apparent ecliptic longitude Horizons gives (its quantity 31).

Rahu (the mean node) agrees with an independent calculation to within 0.19″. Every row of the test set carries the Horizons request that produced it, so anyone can open it and see the same number.

Sunrise and sunset

Sunrise sets the day for the panchang and the start of Rahu Kaal, Choghadiya and the other periods of the day. We compared our sunrise and sunset with the US Naval Observatory for New Delhi, Mumbai, Kolkata, Chennai, Ahmedabad, London and New York on 15 January, 20 March, 15 May, 21 June, 22 September and 21 December 2026.

Against an independent calculation that keeps the seconds, every one of the 84 times agreed to within 3.8 seconds.

Panchang end times

For New Delhi, from the sunrise of 1 November to the sunrise of 1 December 2026, we listed every end time the daily panchang shows: 32 tithis, 30 nakshatras, 33 yogas and 62 karanas. Each was worked out again independently.

None was missing, none was extra, and the element in force at each sunrise was the same on all 30 days. The panchang prints times cut to the minute (a tithi ending at 2:39:58 pm shows as 2:39 pm), never rounded up.

Festival dates

Each festival page states its rule: which tithi, at which time of day (sunrise, moonrise, pradosh or midnight), in which month. For the Kartika season of 2026, from Ahoi Ashtami to Dev Diwali, in 39 Indian cities, plus New Delhi for 2027 and several cities abroad, we worked out every date and puja time again from the rule alone. All 2,495 checks agree; the largest gap is 32 seconds inside the printed minute.

Rising degree, dasha dates and the ayanamsa

• Lagna: for 100 births from 1950 to 2010 in Indian cities, our rising degree is within 0.33″ of an independent calculation, and never in a different sign.
• Mahadasha dates: for 20 births and 10 periods each, the order of the periods is the same in every case and the start times agree to within 65 minutes over a lifetime. A start that falls close to midnight can therefore show on the neighbouring date. We use a year of 365.2425 days; programs that use 365.25 or 360 days will drift apart from us by a few days over a lifetime, and neither choice is a mistake.
• Ayanamsa: our Lahiri value agrees with an independent calculation to within 0.14″ in every year we checked:

The conventions we chose

Two careful calculations can still differ by a minute because they follow different conventions. These are ours:

• Sunrise is when the upper edge of the Sun appears on the horizon, with the usual allowance for the bending of light by the air, at sea level. Some panchangs use the centre of the Sun instead, which gives a sunrise about a minute later.
• Moonrise is when the centre of the Moon reaches the horizon, without the allowance for the air. Almanacs that use the upper edge give a moonrise 4 to 9 minutes earlier.
• The day’s tithi, nakshatra and yoga are the ones running at local sunrise. A festival follows its own rule (sunrise, moonrise, pradosh or midnight), so a city far to the west can keep it on a different date.
• Ayanamsa: Lahiri, 23° 15′ 00.658″ on 21 March 1956, including nutation. Other ayanamsas (KP, Raman, True Chitra) are available on the transits page.
• Rahu and Ketu: the mean node. The true node can differ by up to about a degree and a half.
• Dasha year: 365.2425 days.
• Time zones: the IANA database. It does not record the local times of Bombay and Calcutta used before 1955, so check the offset shown for births in those years.
• Range: 1900 to 2074. For dates decades ahead, nobody knows the slowing of the Earth’s spin exactly, so clock times far in the future carry an uncertainty of several seconds that no program can remove.

What we have not checked independently yet

These parts follow classical rules or our own wording, and we have not yet measured them against an outside reference:

• the wording of yogas, doshas, predictions and remedies
• muhurat choice and scoring (the sunrise and panchang they rest on are checked above)
• Rahu Kaal, Yamaganda, Gulika, Abhijit, Choghadiya and Hora boundaries, beyond the sunrise and sunset they are built from
• moonrise times across the year
• festivals outside the Kartika season, eclipses, and the naming of extra (adhika) months
• divisional charts and the 36-guna matching score
• the Jain pachkhan times, beyond the sunrise they start from
• the Western astrology, numerology, tarot and Vastu tools
• answers given by the AI chat

We will add these as they are measured, with the date of each run.

Download the test set

Everything above can be checked. The files are plain CSV, free to use under CC BY 4.0, with a short guide:

• Planet positions against NASA JPL Horizons (200 rows, each with its Horizons request)
• Sunrise and sunset against the US Naval Observatory (84 times)
• Panchang end times, New Delhi, November 2026 (157 end times)
• Rising degree for 100 births
• Mahadasha start times for 20 births
• Lahiri ayanamsa, 1900 to 2075
• Read me: columns, conventions and how to reproduce

Found a different number?

Tell us through the contact page: the date, time and place, the tool, the number you expected and where it came from. We check every report against the references on this page.

Sources

• Giorgini, J.D. and JPL Solar System Dynamics Group, NASA/JPL Horizons On-Line Ephemeris System, data retrieved 31 October 2026.
• Park, R.S., Folkner, W.M., Williams, J.G. and Boggs, D.H., “The JPL Planetary and Lunar Ephemerides DE440 and DE441”, The Astronomical Journal 161:105 (2021).
• US Naval Observatory, Astronomical Applications Department, rise, set and transit times.
• NASA, JPL and the US Naval Observatory do not endorse this site.