Graha Yuddha periods

calendar.graha-yuddha

Planetary-war entry, closest approach, victor, and exit are derived for tara graha pairs.

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

Scan every selected Tara-graha pair for geocentric longitude separation below one degree, refine threshold crossings and closest approach, then choose the more northerly planet as victor.

Process

1. Generate unordered pairs from Mercury, Venus, Mars, Jupiter, and Saturn.
2. Scan at six-hour steps from 120 days before the range through 60 days after it.
3. When angular separation crosses one degree, bisect the entry or exit with 44 iterations.
4. Ternary-search the enclosed interval for minimum separation.
5. Compare ecliptic latitudes at that instant; the greater latitude wins, and retain only periods overlapping the requested range.

Formulae

War admission

delta = min(abs(lambda_1-lambda_2) mod 360, 360-(abs(lambda_1-lambda_2) mod 360)); in_war = delta < 1 degree

• lambda_1, lambda_2: geocentric ecliptic longitudes

Worked example

Venus-Jupiter, June 2026

Inputs

• Range: 2026-06-01 through 2026-06-30
• Pair: Venus and Jupiter

Calculation

1. The scan brackets entry and exit at the one-degree threshold.
2. Minimum longitudinal separation rounds to 0.000 arcminutes.
3. Venus has the greater ecliptic latitude at closest approach.

Result

• Starts: 2026-06-08 19:18:54 UTC
• Exact: 2026-06-09 19:59:14 UTC
• Ends: 2026-06-10 20:43:12 UTC
• Winner: Venus; loser: Jupiter

Method notes

• Ayanamsa cancels in pairwise longitude difference, so the implementation uses tropical coordinates for the separation search.

Contract

Owning layer: calendar
Claim kind: textual-rule
Time basis: UTC Julian-day numerical search.

Inputs

• date range
• planetary longitudes and latitudes

Outputs

• entry
• minimum separation
• exit
• winner
• loser

References and evidence

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

Numerical boundaries are tested; the one-degree admission and latitude-victor rules need claim-level registry locators.

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_graha_yuddha.py

Run the linked tests, then the complete offline contract:

python tools/verify_project.py

Public surfaces

• python-library
• mcp

Limitations

• The result implements the project's documented one-degree and latitude rule, not every tradition's definition.

Implementation

• owner: telugu_panchangam/graha_yuddha.py — graha_yuddha_periods

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