Panchangam Reference

Per-instant Panchangam facts ​

panchangam.slot-facts

Active Tithi, Nakshatra, Yoga, Karana, lunar Rashi, Vaaram, and special Yogas are recomputed for a slot.

Assurance ​

LevelCurrent statement
Documented and traceableYes — the canonical record includes the process and a worked example.
Regression or reproduction checkedLinked to 2 repository test file(s).
Independently source-supportedNot independently verified at this level; current behavior is regression-pinned.

Computation method ​

Method type: algorithm

At an arbitrary instant, evaluate the selected engine's Sun and Moon once and derive Tithi, Nakshatra, Yoga, Karana, lunar Rashi, Vaaram, and special-Yoga names without rebuilding a full day.

Process ​

  1. Normalize the datetime to UTC and convert it to Julian day.
  2. Evaluate and normalize engine Sun and Moon; compute elongation.
  3. Apply the 12-degree, 360/27-degree, 6-degree, and 30-degree index formulae used by the daily angas.
  4. Use caller-supplied sunrise Vaaram; only if absent, approximate it from UTC weekday.
  5. Pass Vaaram, Tithi, and Nakshatra names to the special-Yoga table.

Worked example ​

Hyderabad sunrise instant, 2026-06-11, Drik Ganita ​

Inputs

  • Instant: 2026-06-11 05:41:11 IST
  • Sun/Moon: 55.8893662040/358.4708221648 degrees
  • Vaaram supplied: Guruvaram

Calculation

  1. Apply all five index formulae at that instant.
  2. Evaluate special Yogas from Guruvaram and the derived Tithi/Nakshatra.

Result

  • Krishna Ekadashi, Revati, Shobhana, Bava, Meena, Guruvaram
  • Special-Yoga list is table-derived from those exact slot facts

Method notes ​

  • The UTC-weekday fallback is approximate around the local sunrise boundary.
  • The browser mirror implements Drik/Lahiri slot facts only.

Contract ​

Owning layer: engine-core
Claim kind: deterministic-fact
Time basis: Exact evaluated instant; Vaaram remains anchored to the Panchangam sunrise day.

Inputs ​

  • instant
  • location
  • engine longitude functions
  • sunrise-anchored Vaaram

Outputs ​

  • slot-time Panchangam facts

References and evidence ​

Evidence classes: astronomical, textual
Verification states: partially_verified, engine_pinned

Slot facts inherit the evidence state of the selected engine and calendar semantics.

drik.sidereal_positions ​

Evidence class: astronomical
Verification state: partially_verified
Locator: Swiss Ephemeris Programmer's Documentation sections 3, 5.8 and 12.2 for calc_ut, sidereal flags and ayanamsa modes; representative date checks in tests/test_drik_engine.py and tests/test_ayanamsa.py
Last reviewed: 2026-08-27
Scope: Traces the Drik longitude API and preserves representative outputs. The current register does not contain an exhaustive independently published position-and-transition fixture, and it establishes no interpretive doctrine.

Sources ​

  • Swiss Ephemeris — Astrodienst; Swiss Ephemeris 2.10 Programmer's Documentation and pyswisseph runtime used by the repository; authority type: astronomical_reference
  • Drik Panchang day and festival pages — Drik Panchang; Location- and date-specific web pages; authority type: published_panchangam

panchangam.non_drik_engine_outputs ​

Evidence class: astronomical
Verification state: engine_pinned
Locator: tests/test_surya_siddhanta_engine.py and tests/test_vakya_engine.py

Scope: Regression tests preserve the current Surya Siddhanta and Vakya Pancha-Anga and sky-event outputs. No independent published-Panchangam comparison set is registered, so engine-pinned output must not be described as externally verified.

Sources ​

  • No external source is registered for this claim.

panchangam.calendar_semantics ​

Evidence class: textual
Verification state: needs_locator
Locator: No precise locator is registered.

Scope: Samvatsara, Ayana, Ritu, lunar-month, Paksha, weekday and Rasi labels combine astronomical calculations with calendar rollover conventions. They require criterion-level locators and regional-scope notes; astronomical correctness alone does not verify the naming convention.

Sources ​

  • Muhurtha (Electional Astrology) — B. V. Raman; UBS Publishers' Distributors, 1993, ISBN 9788185674681, 181 catalogued pages; authority type: modern_synthesis

The complete machine-readable source registry is available in provenance.json. A regression fixture or same-code reproduction is not independent verification.

Reproduce and review ​

Run the linked tests, then the complete offline contract:

bash
python tools/verify_project.py

Public surfaces ​

  • python-library
  • mcp
  • website

Limitations ​

  • The browser mirror currently implements Drik/Lahiri only for slot scoring.

Implementation ​

This route is generated from computations.json. Edit the registry and canonical reference prose in the same pull request as a behavior change.