Yamagandam

panchangam.yamagandam

A weekday table selects one of eight proportional daytime segments.

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	Partial support only; read the provenance note and limitations before generalizing.

Computation method

Method type: decision-table

Select a weekday-specific 1-based eighth of local daylight from the Yamagandam table.

Process

1. Map weekday 0=Sunday through 6=Saturday to Yamagandam part [5, 4, 3, 2, 1, 7, 6].
2. Compute daylight block size as (sunset - sunrise) / 8.
3. Return the selected contiguous block as whole-second UTC instants.

Formulae

Day-part window

B = (sunset - sunrise) / 8
start = sunrise + (part - 1) * B
end = start + B

• part: weekday-selected Yamagandam index
• B: one-eighth daylight duration

Worked example

Hyderabad, Thursday 2026-06-11

Inputs

• Weekday index: 4
• Yamagandam part: 1
• Sunrise/sunset: 05:41:11/18:50:12 IST

Calculation

1. B = 13:09:01 / 8 = 01:38:37.625.
2. Take the first block from sunrise.

Result

• Yamagandam: 05:41:11-07:19:48 IST

Method notes

• The weekday table is conventional; location changes the result only through sunrise and sunset.

Contract

Owning layer: engine-core
Claim kind: textual-rule
Time basis: One eighth of local sunrise-to-sunset daytime.

Inputs

• weekday
• sunrise
• sunset

Outputs

• Yamagandam start/end

References and evidence

Evidence classes: textual, published_panchangam
Verification states: partially_verified

Representative city/date values are independently compared.

panchangam.mixed_daily_windows

Evidence class: textual
Verification state: partially_verified
Locator: B. V. Raman, Chapter III, Nakshatra Tyajyakala table, inspected in the 2020 Chistabo derivative at internal printed p. 7 (physical PDF p. 10), and Chapter V section 7, Durmuhurta, internal printed p. 13 (physical PDF p. 16); regional tables remain regression-pinned
Last reviewed: 2026-09-04
Scope: The auspicious, inauspicious and Choghadiya response objects are mixed containers. Raman supports the four-Ghati Nakshatra Tyajyakala concept and his printed Durmuhurta scheme, but the project's regional weekday tables are not identical to Raman's table and the remaining Brahma Muhurta, Abhijit, Amrita Kalam, Rahu Kalam, Gulika, Yamagandam and Choghadiya components do not yet have criterion-level textual claims. This state records partial evidence, not umbrella verification.

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
• Muhurta Chintamani — Rama Daivajna; Undated Sanskrit text with Hindi commentary, Internet Archive identifier muhurta-chintamani-hindi; authority type: primary_text_hindi_commentary

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_muhurta_windows.py

Run the linked tests, then the complete offline contract:

python tools/verify_project.py

Public surfaces

• python-library
• mcp
• ics
• website

Limitations

• Weekday-part tables are conventional and location-specific through sunrise/sunset.

Implementation

• owner: telugu_panchangam/engines/base.py — PanchangamEngine._yamagandam

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