Hindu Calendar NZ

Monorepo for hinducalendar.co.nz.

packages/
  panchang-engine/   Location-aware Panchang calculation engine (Webfit Solutions Limited)
  calendar-data/     Data access layer used by the website (JSON now, database later)
scripts/
  generate-year.ts   Generates a year of data for a city
data/<year>/<city>/  Generated output (status CALCULATED — not reviewed)
apps/web/            Website (Next.js) — to be added

Generate data

npm install
npx tsx scripts/generate-year.ts --year 2027 --city auckland
npm test

Output in data/2027/auckland/:

File	Contents
days.json	Every civil date: sunrise, sunset, moonrise/set, tithi at sunrise (+ end time), kshaya tithi, nakshatra, amanta/purnimanta month, adhika flag, sun rashi
festivals.json	Festival and vrat dates with rule basis, timing windows, Ekadashi parana and reviewer flags
moon-phases.json	Principal moon phases, local time
sankrantis.json	Solar ingresses with observed date

How dates are calculated

• Tithi: geocentric Moon–Sun elongation ÷ 12° (astronomy-engine, MIT). Independent of ayanamsa.
• Sunrise/sunset/moonrise: local horizon, upper limb, standard refraction, for the city's coordinates; times in the city's IANA zone (NZ daylight saving handled automatically).
• Months: amanta (new moon to new moon), named by the sidereal sun sign at the starting new moon; adhika month when no sankranti falls inside it. Purnimanta names provided for Krishna paksha.
• Nakshatra / sankranti: sidereal positions using a Lahiri ayanamsa approximation (±0.01°, a few minutes on sankranti times).
• Festivals: each rule names a lunar month, paksha, tithi and the part of the day (karmakala) in which the tithi must prevail — sunrise, purvahna, madhyahna, aparahna, sunset, pradosh, nishita or moonrise. Ties, partial coverage and kshaya cases are flagged, not hidden.
• Ekadashi: Smarta date = Ekadashi at sunrise; Vaishnava date via the Dashami-viddha (arunodaya) rule; parana after Hari Vasara within pratahkala and before Dwadashi ends.

Editorial status — important

The engine only ever produces CALCULATED. Moving a record to REVIEWED, APPROVED or PUBLISHED is an editorial decision made by the nominated religious reviewer. The website must only present APPROVED/PUBLISHED records as final guidance (isPublic() in calendar-data).

Database (later phase)

All page code reads through the CalendarStore interface in packages/calendar-data. Phase 1 uses JsonFileStore. A Postgres/Supabase store can implement the same interface when user accounts, reminders, more cities or sponsor management are added.

Ownership

packages/panchang-engine is general-purpose technology of Webfit Solutions Limited and contains no project-specific editorial material. Editorial content, approved datasets and branding for Hindu Calendar NZ are handled under the parties' Heads of Agreement.

Confidential third-party material (e.g. draft calendars supplied by other parties) must not be committed to this repository — keep it in private/ (git-ignored).