We don't copy times from a book. We compute them directly from the real position of the sun and moon for your city.
Sun times
Sunrise and sunset use the NOAA solar algorithm. Rahu kalam, Yamagandam and Kuligai are found by dividing the daylight into eight equal parts and taking the part that belongs to that weekday.
Tithi & Nakshatra
The tithi comes from the sun–moon angular difference, and the nakshatra from the moon's position (Meeus method; Lahiri ayanamsa).
Calendar & festivals
The Tamil date and festivals follow Tamil Nadu time, the same day across the world. Only the sun times are for your city. The main festival dates are taken from a trusted panchangam and cross-checked against our own calculation.
What we show
We compute nalla neram from the Gowri Panchangam and your city's sun times, and we mark any window that falls inside rahu kalam, yamagandam or kuligai instead of presenting it as simply good. Named annual festivals are curated from an authoritative panchangam and cross-checked against our own astronomy, because their observance rules cannot be derived from a sunrise rule alone. Where we cannot verify something, we don't show it — better to show nothing than the wrong time.
Comparing with the temple almanac
We cross-check our calculations against the temple's printed panchangam.
How accurate is it?
We measure it rather than claim it. Against the US Naval Observatory's published times, Chennai's sunrise and sunset land within a minute on every day we checked, and so do moonrise and moonset. The sharpest test of a tithi is the exact moment of new or full moon: across 195 of them from 1900 to 2050 our average error is under three seconds and the worst is 39. After 2050 the drift is ΔT — how far the Earth's rotation will have slipped, which nobody can measure in advance — reaching about a minute and three quarters by 2100. The Tamil month turns when the Sun enters a new sign, and there a second thing decides the answer: the ayanamsa, the offset between the tropical and the sidereal zodiac. Against 84 of those ingresses published by Drik Panchang between 2017 and 2033, we land within a minute and a half of every one, and within a single minute of 78. And on what a day page actually shows: across 44 days sampled through 2026 and 2027, every tithi, nakshatra and yoga we name is the one Drik names, and every end time is within a minute of theirs. The comparison runs in our test suite, so it cannot quietly stop being true.
Thirukanitha and Vakiya, which system does this site use?
Tamil panchangam comes in two traditions. Vakiya panchangam uses fixed astronomical constants from ancient manuscripts, the same values temple almanacs have printed for centuries. Thirukanitha panchangam (also spelled Drigganita) computes positions directly from modern astronomical algorithms, tracking the actual observed positions of Sun and Moon. This site uses the Thirukanitha method. For the diaspora, precision matters: sunrise and rahu kalam differ by several minutes between cities just one degree of longitude apart. A calculation anchored to real astronomy, for your city's exact coordinates, gives more reliable times than a manuscript table built for a single location.
Frequently asked questions
Sun times
Sunrise and sunset use the NOAA solar algorithm. Rahu kalam, Yamagandam and Kuligai are found by dividing the daylight into eight equal parts and taking the part that belongs to that weekday.
Tithi & Nakshatra
The tithi comes from the sun–moon angular difference, and the nakshatra from the moon's position (Meeus method; Lahiri ayanamsa).
Calendar & festivals
The Tamil date and festivals follow Tamil Nadu time, the same day across the world. Only the sun times are for your city. The main festival dates are taken from a trusted panchangam and cross-checked against our own calculation.
Comparing with the temple almanac
We cross-check our calculations against the temple's printed panchangam.
How accurate is it?
We measure it rather than claim it. Against the US Naval Observatory's published times, Chennai's sunrise and sunset land within a minute on every day we checked, and so do moonrise and moonset. The sharpest test of a tithi is the exact moment of new or full moon: across 195 of them from 1900 to 2050 our average error is under three seconds and the worst is 39. After 2050 the drift is ΔT — how far the Earth's rotation will have slipped, which nobody can measure in advance — reaching about a minute and three quarters by 2100. The Tamil month turns when the Sun enters a new sign, and there a second thing decides the answer: the ayanamsa, the offset between the tropical and the sidereal zodiac. Against 84 of those ingresses published by Drik Panchang between 2017 and 2033, we land within a minute and a half of every one, and within a single minute of 78. And on what a day page actually shows: across 44 days sampled through 2026 and 2027, every tithi, nakshatra and yoga we name is the one Drik names, and every end time is within a minute of theirs. The comparison runs in our test suite, so it cannot quietly stop being true.
What we show
We compute nalla neram from the Gowri Panchangam and your city's sun times, and we mark any window that falls inside rahu kalam, yamagandam or kuligai instead of presenting it as simply good. Named annual festivals are curated from an authoritative panchangam and cross-checked against our own astronomy, because their observance rules cannot be derived from a sunrise rule alone. Where we cannot verify something, we don't show it — better to show nothing than the wrong time.
Sources
External references. All timings on this page come from this site's own astronomical calculation.
- Jean Meeus, Astronomical Algorithms, 2nd ed., Willmann-Bell, 1998.
- NOAA Solar Calculator
- N. C. Lahiri, Indian Astronomical Ephemeris; Chitrapaksha ayanamsa adopted by the Indian Calendar Reform Committee, 1957.
- Tamil Nadu Government Gazette — official list of public holidays and festival dates.