Ruling · Dattātreyotpatti (Dattātreya Jayantī) · 1981

Thursday 10 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 Thursday 10 December

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

16:56 sunsetpradoṣa ends 18:52
16:3216:5617:2017:4418:0818:3218:5619:20

0 of 116 minutes covered

Evening of Friday 11 December

Pūrṇimā is absent from pradoṣa. Not taken.

16:56 sunsetpradoṣa ends 18:52
Pūrṇimā ends 16:41:21
16:3216:5617:2017:4418:0818:3218:5619:20

0 of 116 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 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: 16:56–18:52 on the 10th, 16:56–18:52 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 116 minutes on the 10th and 0 of 116 on the 11th.

    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 875 s

  5. 05

    Ruling

    Dattātreyotpatti, Baoding, 1981: Thursday 10 December.

    confidence: boundary (absent-unstated)

Say it like this

In Baoding, Dattātreyotpatti (Datta Jayanti) 1981 falls on Thursday 10 December. Pūrṇimā runs from 20:31 on Thu 10 Dec to 16:41 on Fri 11 Dec, and reaches pradoṣa on neither day.

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

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingThu 10 Dec
Ahargaṇa, classicalDisc centre, no refractionThu 10 Dec
compat-drikpanchangComparison profileThu 10 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 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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