Panchangam Reference

Nitya Yoga span ​

panchangam.nitya-yoga

The normalized sum of solar and lunar longitude selects one of 27 Nitya Yogas.

Assurance ​

LevelCurrent statement
Documented and traceableYes — the canonical record includes the process and a worked example.
Regression or reproduction checkedLinked to 3 repository test file(s).
Independently source-supportedNot independently verified at this level; current behavior is regression-pinned.

Computation method ​

Method type: formula

Add the selected engine's Sun and Moon longitudes modulo one revolution, divide the result into 27 equal Yoga sectors, and solve the enclosing crossings around sunrise.

Process ​

  1. Compute combined longitude Y=(S+M) modulo 360.
  2. Set N=360/27 and y=floor(Y/N) modulo 27.
  3. Bisect the combined-longitude function at y*N before sunrise and at (y+1)*N after sunrise, each within a two-day window.
  4. Map y through YOGA_NAMES and return whole-second UTC boundaries.

Formulae ​

Nitya Yoga index ​

text
Y = (S + M) mod 360
y = floor(Y / (360 / 27)) mod 27
  • S: engine Sun longitude
  • M: engine Moon longitude
  • y: Yoga index

Worked example ​

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

Inputs

  • Sun: 55.8893662040 degrees
  • Moon: 358.4708221648 degrees

Calculation

  1. Y=(55.8893662040+358.4708221648) modulo 360 = 54.3601883689 degrees.
  2. floor(Y/13.3333333333)=4, Shobhana.
  3. Solve the adjacent combined-longitude crossings.

Result

  • Shobhana
  • Span: 2026-06-11 04:03:08 to 2026-06-12 01:00:09 IST

Method notes ​

  • The selected Sun/Moon model controls both classification and transition times.

Contract ​

Owning layer: engine-core
Claim kind: deterministic-fact
Time basis: Active at local sunrise with UTC crossing search.

Inputs ​

  • solar longitude
  • lunar longitude

Outputs ​

  • Nitya Yoga name and boundary

References and evidence ​

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

Drik has representative comparisons; non-Drik spans are engine-pinned.

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
  • ics
  • website

Limitations ​

  • This is the 27-part Nitya Yoga, not every other named Yoga vocabulary.

Implementation ​

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