Sunrise-anchored Vaaram

panchangam.vaaram

The weekday is selected for the Panchangam day and remains constant until the next sunrise.

Assurance

Level	Current statement
Documented and traceable	Yes — the canonical record includes the process and a worked example.
Regression or reproduction checked	Linked to 2 repository test file(s).
Independently source-supported	Not recorded as independently verified. The disclosed provenance state remains authoritative.

Computation method

Method type: formula

Derive weekday from sunrise Julian day and hold that Vaaram constant for the complete sunrise-to-next-sunrise Panchangam day.

Process

1. Compute location/date sunrise as a UT Julian day.
2. Set weekday index to int(JD_sunrise+1.5) modulo 7, where 0=Sunday.
3. Map through VAARAM_NAMES and attach the single name to the day.
4. Pass the same value into slot-time facts so it does not flip at civil midnight.

Formulae

Sunrise weekday

weekday = int(JD_sunrise + 1.5) mod 7

• JD_sunrise: UT Julian day of local sunrise
• weekday: Sunday=0 through Saturday=6

Worked example

Hyderabad, 2026-06-11

Inputs

• Sunrise JD: 2461202.5077662035

Calculation

1. int(2461202.5077662035+1.5) modulo 7 = 4.
2. VAARAM_NAMES[4] is Guruvaram.

Result

• Guruvaram from sunrise 2026-06-11 until the next sunrise

Method notes

• Before local sunrise, civil-date weekday expectations can differ from active Panchangam Vaaram.

Contract

Owning layer: engine-core
Claim kind: regional-convention
Time basis: Sunrise-to-next-sunrise day, not civil midnight.

Inputs

• local Panchangam date and sunrise

Outputs

• Vaaram name

References and evidence

Evidence classes: textual, regional_convention
Verification states: needs_locator

The sunrise-day semantic is tested but needs an exact textual locator.

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

• tests/test_engine_facts_at.py
• tests/test_drik_engine.py

Run the linked tests, then the complete offline contract:

python tools/verify_project.py

Public surfaces

• python-library
• mcp
• ics
• website

Limitations

• Civil-midnight weekday expectations can differ before local sunrise.

Implementation

• owner: telugu_panchangam/engines/drik.py — DrikGanitaEngine.calculate
• owner: telugu_panchangam/engines/surya_siddhanta.py — SuryaSiddhantaEngine.calculate
• owner: telugu_panchangam/engines/vakya.py — VakyaEngine.calculate

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