Sankramana avoidance window

derived.sankramana-avoidance

A symmetric sixteen-Ghati interval is placed around exact solar ingress.

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	Available only for the explicitly named provenance claims or comparison cells.

Computation method

Method type: formula

Center a symmetric window of sixteen local proportional Ghatis on the exact solar-ingress instant.

Process

1. Return null when the Panchangam day has no solar ingress.
2. Read seconds per Ghati from the sunrise-to-next-sunrise clock.
3. Multiply by 16 for the half-width.
4. Subtract and add that half-width around the ingress instant.

Formulae

Sankramana avoidance

W = 16*s_g; start = ingress - W; end = ingress + W

• s_g: seconds per proportional Ghati
• W: half-width

Worked example

Mithuna ingress, Hyderabad 2026-06-15

Inputs

• Ingress: 12:53:00 IST
• Seconds per Ghati: 1,440.15

Calculation

1. 16 * 1,440.15 seconds = 6h24m02.4s per side.
2. Apply symmetrically around the ingress.

Result

• Avoidance: 06:28:57-19:17:02 IST

Method notes

• The same sixteen-Ghati half-width is used for all signs; alternative solstitial conventions are not blended.

Contract

Owning layer: derived
Claim kind: textual-rule
Time basis: Sixteen proportional Ghatis before and after ingress.

Inputs

• solar ingress instant
• Ghati clock

Outputs

• avoidance start and end

References and evidence

Evidence classes: textual
Verification states: verified

The duration and placement have registered textual evidence.

panchangam.sankramana_avoidance

Evidence class: textual
Verification state: verified
Locator: B. V. Raman, Chapter V section 2, 'Surya Sankramana,' inspected in the 2020 Chistabo derivative at internal printed pp. 12-13 (physical PDF pp. 15-16); the exact 16-Ghati rule is on internal printed p. 13 (physical PDF p. 16)
Last reviewed: 2026-09-04
Scope: Supports rejecting sixteen Ghatis before and after Surya enters a new Rasi for new work. The implementation scales a Ghati to the local sunrise-to-next-sunrise Panchangam day. It does not implement any sign-specific longer Sankramana interval.

Sources

• Muhurtha (Electional Astrology) — B. V. Raman; UBS Publishers' Distributors, 1993, ISBN 9788185674681, 181 catalogued pages; authority type: modern_synthesis
• Muhurtha (Electional Astrology) — Chistabo re-edited derivative — B. V. Raman; re-edited by Simon (Chistabo); 2020 re-edited transcription, 78 physical PDF pages; authority type: inspected_derivative

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_sankramana_window.py

Run the linked tests, then the complete offline contract:

python tools/verify_project.py

Public surfaces

• python-library
• mcp
• website

Limitations

• The window is a textual election rule, not uncertainty around the astronomical crossing.

Implementation

• owner: telugu_panchangam/sankramana.py — compute_sankramana_window

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