सरल शब्दों मेंIn plain words
Your panchang and festival dates, in plain words.
Where do the dates come from?
From our own panchang engine. The positions of the planets are computed in our own code from published astronomical theories, with no third-party ephemeris library, and every tithi, nakshatra, yoga and karana is worked out from them.
Are the times worked out for my city?
Yes. Sunrise, sunset, Rahu Kaal, choghadiya and the day's other divisions are computed for the city's own latitude, longitude and time offset, never for a national average. Every panchang page names its city; where a page names none, it is Mumbai.
Why does my printed panchang differ by a minute or two?
Mostly because of sunrise. We take sunrise as the moment the upper edge of the Sun meets the horizon, allowing for the way the air bends light, and printed almanacs may differ from our sunrise by about two minutes. On a rare day, that is enough for a printed almanac to name a different tithi for the day. Sankranti times can differ by several minutes too; when one falls close to sunset, check its observance day against your local almanac.
Which city do the festival dates follow?
On the calendar of each city listed on the calendar's front page, festival and vrat dates are computed for that city. Any other city's calendar shows Mumbai's festival dates, and says so once on the page; its sunrise, sunset and other times are still its own. In our festival guides, such as Yantras for Diwali, the festival and order-by dates are computed for Mumbai, the reference city.
Who writes the text below each month?
A language model, from that month's computed calendar and nothing else. Code checks every fact it names, and a second, different model reviews it before it appears. A text that fails is left off the page.
पद्धतिThe method
The method, for the curious.
The ayanamsa is Lahiri.
Every sidereal position on this site (the rashi, the nakshatra, the tithi, the yoga, the karana) is computed with the Lahiri ayanamsa, the standard used by the Indian government's Rashtriya Panchang. Panchangs computed with a different ayanamsa will differ from ours, usually by a fraction of a degree, and occasionally by enough to move a nakshatra boundary across a date line. If a panchang you trust disagrees with ours, the ayanamsa is the first thing to compare.
Lahiri itself has more than one published realisation, and they differ by a few tens of arcseconds. Ours is 23°51′25.5″ at the epoch J2000.0, carried forward by a single precession formula. Sankranti times (the moment the Sun enters a sign) are where that shows: against one widely used almanac, ours ran about eight minutes earlier on every Sankranti of 2026, and every date was the same. If a Sankranti falls within a few minutes of sunset, check its observance day against your local almanac.
The ephemeris.
Planetary positions are computed with our own implementation of published astronomical theories: VSOP87D for the planets and ELP2000-82B for the Moon, checked against the reference ephemerides of NASA's Jet Propulsion Laboratory. Both theories are published scientific data catalogues. We evaluate them in our own code, and no third-party ephemeris library is involved.
The check: JPL DE440s at 2 arcminutes.
Every position function in our code was compared against JPL's DE440s ephemeris, an independent implementation built on an independent dataset, at eleven dates in the span 1930 to 2010. The tolerance is 2 arcminutes, and the largest difference measured was 0.35 arcminutes, on the Moon's node. That is comfortably inside the precision a panchang needs: a tithi boundary moves at about twelve degrees a day.
Outside those years, the positions have not been measured against JPL, and we do not claim they have. For a date centuries away, or for work where arcsecond provenance matters, use a dedicated ephemeris.
Sunrise, sunset and location.
Timings that depend on the horizon (sunrise, sunset, Rahu Kaal, choghadiya, the day's divisions) are computed for a specific city's latitude, longitude and offset, not for a national average. A panchang page names the city it was computed for. Where a page does not name one, it is Mumbai.
Sunrise and sunset are the moments the upper edge of the Sun meets the horizon, allowing for atmospheric refraction (the standard altitude of −0.833°). Almanacs that print a slightly later sunrise can, on a rare day, name a different tithi for that day than we do. Printed almanacs may differ from our sunrise by about two minutes.
Months, years and festival dates in the calendar.
Each city's calendar states its convention in words below the month. Unless a city's page names another, months are reckoned amanta (each month ends at the new moon), years are given in Shaka Samvat, the ayanamsa is Lahiri, and festival dates follow the Smarta tradition.
On the calendar of each city listed on the calendar's front page, festival and vrat dates are computed for that city. Any other city's calendar shows Mumbai's festival dates and says so once on the page. A city's sunrise, sunset and other times are always its own.
The text on each month's back page.
Below a month's calendar, the back page explains its main festivals, reads the month for each Moon sign and notes its eclipses and seasons. That text is written by a language model, separately in English, Hindi and Marathi, never translated from one to another, and only from that month's computed calendar: the dates, tithis, lunar months and planetary positions stored for the page.
Code then checks it against those facts. Every date, time, number, tithi, nakshatra, month, sign and planet it names must be one the facts give, in that language's spelling, within set lengths, and with no promised outcome. A second, different model then reviews it for fact, language and tone. A text appears only when it has passed both; one that fails is left off the page rather than shown with a warning.
Muslim festival dates.
A Muslim month begins when the new crescent is sighted, which in India can be a day later than the tabular Islamic calendar predicts. We take each month's first day from the month starts published for the year. Beyond the published months, we show the date the tabular calendar expects, marked "expected, subject to sighting", until that year's starts are published.
What we will not put on a page.
We do not publish a composite "day out of ten" number, and we do not grade a day. The tradition states what a given window is and what it is customarily used for. A single number blending several such windows would be our own invention, set in the same type as a real tithi, and a reader would have no way to tell the two apart. Where we report a count, such as how many notable timings a day carries, it is a count, and it is never shown as a share of an invented maximum.
Found a value that looks wrong?
If a computed value on this site disagrees with a source you trust, tell us which page, which value, which city and which date, and which panchang you compared it against. That is enough for us to reproduce it. Write to hello@bhagya.cards; we reply within one business day, in English, Hindi or Marathi.