Ruling · Dattātreyotpatti (Datta Jayanti) · 1981

Friday 11 December

Determinatein Daqing, under the Rashtriya Panchang method. Clear of every threshold by 49 minutes.

Decide it for

DaqingDelhiKolkataSingaporeSydneyJersey City

46°35′ N 125°00′ E · Asia/Shanghai · GeoNames 2037860

The two evenings

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

Evening of Thursday 10 December

Pūrṇimā is absent from pradoṣa. Not taken.

15:52 sunsetpradoṣa ends 17:55
15:2815:5216:1616:4017:0417:2817:5218:16

0 of 123 minutes covered

Evening of Friday 11 December

Taken. The only evening Pūrṇimā reaches.

15:52 sunsetpradoṣa ends 17:55
Pūrṇimā ends 16:41:21
15:2815:5216:1616:4017:0417:2817:5218:16

49 of 123 minutes covered, the first 49

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

How it was decided

  1. 01

    Aṅga

    Pūrṇimā runs from 20:31 on Thu 10 Dec to 16:41 on Fri 11 Dec.

    1981-12-10T12:30:52Z → 1981-12-11T08:41:21Z

  2. 02

    Kāla

    Pradoṣa is 2 muhūrtas after sunset: 15:52–17:55 on the 10th, 15:52–17:55 on the 11th.

    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 123 minutes on the 10th and 49 of 123 on the 11th.

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

  4. 04

    Tie-break

    Only one evening qualifies. No tie-break is needed.

    priority: unstated → only-day · margin 2957 s

  5. 05

    Ruling

    Dattātreyotpatti, Daqing, 1981: Friday 11 December.

    confidence: determinate

Say it like this

In Daqing, Dattātreyotpatti (Datta Jayanti) 1981 falls on Friday 11 December. Pūrṇimā runs from 20:31 on Thu 10 Dec to 16:41 on Fri 11 Dec and covers 49 of 123 minutes of pradoṣa that evening.

ahargana.org/daqing/festivals/1981/dattatreyotpatti · pac-rp@2026.1

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingFri 11 Dec
Ahargaṇa, classicalDisc centre, no refractionFri 11 Dec
compat-drikpanchangComparison profileFri 11 Dec
No institution has a recorded ruling for Daqing.

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 10thCoveredSunset 11thCoveredRuled
Los Angeles04:31 → 00:4116:44113 min16:440 min10 Dec
Chicago06:31 → 02:4116:19119 min16:190 min10 Dec
Jersey City07:31 → 03:4116:29118 min16:290 min10 Dec
Port of Spain08:31 → 04:4117:44100 min17:450 min10 Dec
London12:31 → 08:4115:51129 min15:510 min10 Dec
Durban14:31 → 10:4118:4980 min18:500 min10 Dec
Dubai16:31 → 12:4117:30107 min17:300 min10 Dec
Delhi18:01 → 14:1117:2473 min17:250 min10 Dec
Kolkata18:01 → 14:1116:5338 min16:530 min10 Dec
Singapore20:01 → 16:1118:293 min18:290 min10 Dec
Sydney23:31 → 19:4119:580 min19:590 min10 Dec
Suva00:31 → 20:4118:340 min18:3587 min11 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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