Ruling · Dattātreyotpatti (Dattātreya Jayantī) · 1990

Saturday 1 December

Boundaryin Baoding, under the Rashtriya Panchang method. Pūrṇimā reaches pradoṣa on neither day and the rule does not say what then. Say “contested”.

Decide it for

BaodingDelhiKolkataSingaporeSydneyJersey City

38°52′ N 115°28′ E · Asia/Shanghai · GeoNames 1816971

The two evenings

One ghaṭī is 24 minutes. Pradoṣa is 2 muhūrtas after sunset.

Evening of Saturday 1 December

Taken. Pūrṇimā reaches neither evening; this is the day it falls on.

16:56 sunsetpradoṣa ends 18:51
16:3216:5617:2017:4418:0818:3218:5619:20

0 of 115 minutes covered

Evening of Sunday 2 December

Pūrṇimā is absent from pradoṣa. Not taken.

16:56 sunsetpradoṣa ends 18:51
16:3216:5617:2017:4418:0818:3218:5619:20

0 of 115 minutes covered

Pūrṇimā presentPradoṣa, the window the rule readsThe instant the tithi begins or ends

How it was decided

  1. 01

    Aṅga

    Pūrṇimā runs from 19:42 on Sat 1 Dec to 15:50 on Sun 2 Dec.

    1990-12-01T11:41:48Z → 1990-12-02T07:49:40Z

  2. 02

    Kāla

    Pradoṣa is 2 muhūrtas after sunset: 16:56–18:51 on the 1st, 16:56–18:51 on the 2nd.

    pradosha: night-muhurta-1-2 · sunrise and sunset: upper limb, 31′ + 16′

  3. 03

    Rule

    Pūrṇimā must be present during pradoṣa. It covers 0 of 115 minutes on the 1st and 0 of 115 on the 2nd.

    Calendar Reform Committee 1955, General Rules for Religious Festivals, p. 104

  4. 04

    Tie-break

    Neither evening qualifies. The day the tithi falls on is taken.

    priority: unstated → tithi-day · margin 3027 s

  5. 05

    Ruling

    Dattātreyotpatti, Baoding, 1990: Saturday 1 December.

    confidence: boundary (absent-unstated)

Say it like this

In Baoding, Dattātreyotpatti (Datta Jayanti) 1990 falls on Saturday 1 December. Pūrṇimā runs from 19:42 on Sat 1 Dec to 15:50 on Sun 2 Dec, and reaches pradoṣa on neither day.

ahargana.org/baoding/festivals/1990/dattatreyotpatti · pac-rp@2026.1

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingSat 1 Dec
Ahargaṇa, classicalDisc centre, no refractionSat 1 Dec
compat-drikpanchangComparison profileSat 1 Dec
No institution has a recorded ruling for Baoding.

Institutional rulings are recorded with a source address, and are never edited to agree.

The rule, as data

/rules/dattatreyotpatti · ruleset 2026.3-draft

Month
Mārgaśīrṣa, amānta
Pakṣa · aṅga
Śukla · Pūrṇimā
Kāla
Pradoṣa
Priority
Unstated
Tie-break
Longer coverage, as a boundary
Reference
CRC 1955, p. 104

“S 15 Dattatreyotpatti (pradosa).” Calendar Reform Committee 1955, General Rules for Religious Festivals, p. 104.

The same rule, elsewhere

Twelve places, west to east. Local clock times.

PlacePūrṇimāSunset 1stCoveredSunset 2ndCoveredRuled
Los Angeles03:42 → 23:5016:43112 min16:430 min1 Dec
Chicago05:42 → 01:5016:20117 min16:200 min1 Dec
Jersey City06:42 → 02:5016:29116 min16:290 min1 Dec
Port of Spain07:42 → 03:5017:41100 min17:420 min1 Dec
London11:42 → 07:5015:55127 min15:540 min1 Dec
Durban13:42 → 09:5018:4281 min18:430 min1 Dec
Dubai15:42 → 11:5017:28107 min17:280 min1 Dec
Delhi17:12 → 13:2017:23108 min17:230 min1 Dec
Kolkata17:12 → 13:2016:5184 min16:510 min1 Dec
Singapore19:42 → 15:5018:5549 min18:550 min1 Dec
Sydney22:42 → 18:5019:510 min19:510 min1 Dec
Suva23:42 → 19:5018:290 min18:2980 min2 Dec
Profile · tradition
pac-rp@2026.1 · smarta
Rule
dattatreyotpatti@2026.3-draft
Engine · kernel
0.1.0 · de440 7eef…ea74
Boundary margin
300 s

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