Description
Compute geometric tithi index and progress from same-frame geocentric Sun/Moon longitudes using half-open 12-degree elongation bins; no sunrise assignment or ephemeris.
A panchanga uses calendrical labels derived from astronomical positions and conventions. Tithi uses Sun-Moon angular separation, while nakshatra calculations use an explicitly chosen sidereal reference. Classifying supplied angles is separate from computing ephemerides, local sunrise, and calendar-day observances.
Compute geometric tithi index and progress from same-frame geocentric Sun/Moon longitudes using half-open 12-degree elongation bins; no sunrise assignment or ephemeris.
When to use this tool
Use Panchanga Tithi Calculator when you already have the required angular coordinate or tithi ordinal and need this limited classification.
How to use the tool and how it works
- Enter sunLongitudeDegrees, moonLongitudeDegrees. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Require sunLongitudeDegrees and moonLongitudeDegrees within zero through 360. Wrap moon minus sun modulo 360 into elongationDegrees, return tithiOrdinal=floor(elongation/12)+1, and fractionalProgress=(elongation modulo 12)/12 inside result.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| sunLongitudeDegrees | Sun Longitude Degrees | Required. Finite number. |
| moonLongitudeDegrees | Moon Longitude Degrees | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Object containing the calculated result members described below. | Required. Object. |
| result.tithiOrdinal | Tithi Ordinal | Calculated result member: number. |
| result.fractionalProgress | Dimensionless fraction through the current 12-degree interval. | Calculated result member: number. |
| result.elongationDegrees | Elongation Degrees | Calculated result member: number. |
{
"input": {
"sunLongitudeDegrees": 350,
"moonLongitudeDegrees": 8
},
"output": {
"result": {
"tithiOrdinal": 2,
"fractionalProgress": 0.5,
"elongationDegrees": 18
}
}
}Limitations and assumptions
- This classifies a supplied angular separation into 30 equal tithi intervals. It does not compute ephemerides, sunrise, local calendar dates, end times, or a location-specific panchanga; 360-degree inputs wrap to zero.
- Outputs are nested inside result. Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Signed zero is exported as zero.
Alternative or Complementary methods
Use an astronomical ephemeris and a location-appropriate calendrical procedure for actual dates and end times. Verify the sidereal reference, time scale, local sunrise convention, and intended almanac tradition.
References
Similar or alternative tools
- Panchanga Paksha Classifier
Classify a resolved tithi ordinal into waxing Shukla or waning Krishna fortnight and its one-based position, without predicting dates.
- Panchanga Nakshatra Pada Calculator
Resolve an explicitly established sidereal longitude into equal 27-fold nakshatra and quarter/pada bins; no ayanamsha selection or date calculation.