Planetary Asta and Udaya calendar

calendar.combustion-periods

Swiss Ephemeris heliacal events produce per-location combustion setting and rising periods.

Assurance

Level	Current statement
Documented and traceable	Yes — the canonical record includes the process and a worked example.
Regression or reproduction checked	Linked to 1 repository test file(s).
Independently source-supported	Not independently verified at this level; current behavior is regression-pinned.

Computation method

Method type: algorithm

Search Swiss Ephemeris heliacal events with a fixed atmosphere and per-planet observer parameters, pair disappearance with reappearance, and retain periods overlapping the requested range.

Process

1. Validate the planet subset and build observer longitude, latitude, and altitude.
2. Start each search 120 days before the requested range so an already-active Asta is retained.
3. For Mars, Jupiter, and Saturn pair Heliacal Setting with Heliacal Rising; for Mercury and Venus search both superior- and inferior-conjunction event pairs.
4. Advance beyond each exit, convert event Julian days to UTC, filter by overlap, and sort by Asta instant.

Worked example

Saturn Asta/Udaya, Hyderabad 2026

Inputs

• Range: 2026-02-01 through 2026-05-01
• Observer: Hyderabad, altitude 531 m
• Planet: Saturn

Calculation

1. Search Heliacal Setting with Saturn Snellen ratio 5.0.
2. Search Heliacal Rising after entry with ratio 1.0.
3. The resulting pair overlaps the requested range.

Result

• Asta: 2026-03-13 13:17:49 UTC
• Udaya: 2026-04-21 23:43:55 UTC

Method notes

• This is the heliacal-visibility calendar, distinct from the per-day fixed-elongation Maudhya flag.
• The current Hyderabad regression compares Saturn/Jupiter/Venus within about two days; the parameters are model calibration, not universal atmospheric constants.

Contract

Owning layer: calendar
Claim kind: deterministic-fact
Time basis: UTC heliacal event search converted for the requested location.

Inputs

• date range
• location including altitude
• planet

Outputs

• combustion periods with Asta and Udaya instants

References and evidence

Evidence classes: astronomical
Verification states: engine_pinned

Swiss Ephemeris event behavior is tested, but independent event-cell comparisons are not yet registered.

No registered claim ID; the provenance note below is the current disclosure.

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

• tests/test_maudhya_calendar.py

Run the linked tests, then the complete offline contract:

python tools/verify_project.py

Public surfaces

• python-library
• mcp

Limitations

• Heliacal visibility depends on observer, atmosphere, altitude, and Swiss Ephemeris modeling; the current fixed atmosphere and per-planet visibility parameters were tuned against a 2026 Hyderabad comparison set.

Implementation

• owner: telugu_panchangam/maudhya_calendar.py — combustion_periods

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