Does Parashar Jyotisha use Lahiri ayanamsa?
Yes. The sidereal portions of the current Panchang implementation—such as Nakshatra, Yoga and zodiac signs—use Lahiri (Chitrapaksha) sidereal longitudes.
Home / Methodology
Calculation Method
How We Calculate Panchang
A transparent description of the current Parashar Jyotisha Panchang calculation flow: location and sunrise, Sun–Moon geometry, Lahiri sidereal factors, refined transitions and daily timing windows.
Location-awareLahiri siderealSunrise-based dayRefined transitionsTransparent method
Calculation Philosophy
Location first, then the Panchang day
The Panchang page starts from the selected city and date. The calculation resolves geographic coordinates and local time zone, then obtains local sunrise and sunset. Many daily elements are anchored to that local sunrise rather than assuming the civil day begins at midnight.
City & timezoneLocal coordinates and time zone are used so sunrise and daily windows are location-aware.
Sunrise anchorTithi, Nakshatra, Yoga and Karana are reported at sunrise, with transition times when available.
Selected-time viewThe API can also calculate the four moving limbs at a selected local time, useful when a transition occurs during the day.
Astronomical Basis
How the five limbs are derived
| Element | Basis used by this implementation | Practical output |
|---|---|---|
| Tithi | Sun–Moon angular separation. The implementation uses tropical longitudes for the elongation calculation; a common ayanamsa offset cancels in the difference. | Tithi at sunrise, selected-time Tithi and transition/end timing. |
| Karana | Half-Tithi division from the same Sun–Moon angular relationship. | Karana at sunrise, next Karana and transition timing. |
| Nakshatra | Sidereal Moon longitude using Lahiri (Chitrapaksha) ayanamsa. | Nakshatra at sunrise/selected time and transition timing. |
| Yoga | Combination of sidereal Sun and Moon longitudes using Lahiri. | Yoga at sunrise/selected time and transition timing. |
| Vara | Weekday associated with the local Panchang day. | Local weekday shown with the daily result. |
Why mixed tropical/sidereal handling? Tithi and Karana depend on the angular difference between Sun and Moon, so subtracting the same ayanamsa from both does not change their separation. Nakshatra, Yoga and zodiac signs require a sidereal reference, so Lahiri sidereal longitudes are used directly.
Transitions & Timings
Why a Panchang value can change during the day
Tithi, Nakshatra, Yoga and Karana are angular segments, not midnight-to-midnight calendar labels. The calculation therefore searches for the actual transition. Where the refined transition providers are available, the current implementation uses a bisection-style refinement rather than a coarse hourly guess.
Transition filteringTransitions are filtered from local sunrise to the next sunrise so the displayed events belong to the Panchang day.
Readable displaySunrise and sunset are rounded to the nearest minute in the website/API display to match the practical style used in common Panchang references.
Daily Windows
Rahu Kaal, Yamaganda, Gulika and Muhurta
After local sunrise and sunset are known, the system calculates daytime windows such as Rahu Kaal, Yamaganda and Gulika using weekday-dependent daytime segmentation. It also returns Disha Shool and, when applicable, Brahma Muhurta and Abhijit Muhurta.
These timings should be understood as traditional timing aids. A daily window is not equivalent to a personalized Muhurta, which can additionally consider the activity, natal chart and other contextual factors.
Why Results Can Differ
Why two Panchang websites may show slightly different times
CoordinatesDifferent city centres or latitude/longitude choices alter local sunrise and timing windows.
Tradition & ayanamsaDifferent schools may use different ayanamsa or conventions for interpreting a Panchang day.
Rounding & algorithmsRounding, ephemeris settings and transition-search precision can move a displayed time by a small amount.
Validation approach: When we refine the calculation engine, the goal is internal consistency across the website and app plus comparison against established Panchang references. A difference should be investigated rather than hidden.
Use the Tool
Check the calculation for your own city
Common Questions
Panchang methodology FAQ
Why are Tithi and Karana described as tropical?
They depend on Sun–Moon elongation. Applying the same ayanamsa correction to both longitudes leaves their angular difference unchanged.
Are Panchang timings location-dependent?
Yes. Sunrise, sunset and several daily windows depend on the selected location and local time zone.
Why can Tithi end after midnight?
The angular transition follows planetary motion, not the civil clock. The calculation therefore reports transitions that can occur later in the night or before the next sunrise.