Ruling · Dattātreyotpatti (Dattātreya Jayantī) · 2027

Monday 13 December

Determinatein Ujjain, under the Rashtriya Panchang method. Clear of every threshold by 130 minutes.

Decide it for

UjjainDelhiKolkataSingaporeSydneyJersey City

23°11′ N 75°47′ E · Asia/Kolkata · GeoNames 1253914

The two evenings

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

Evening of Sunday 12 December

Pūrṇimā is absent from pradoṣa. Not taken.

17:42 sunsetpradoṣa ends 19:28
17:1817:4218:0618:3018:5419:1819:42

0 of 106 minutes covered

Evening of Monday 13 December

Taken. The only evening Pūrṇimā reaches.

17:42 sunsetpradoṣa ends 19:29
17:1817:4218:0618:3018:5419:1819:42

106 of 106 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 23:56 on Sun 12 Dec to 21:39 on Mon 13 Dec.

    2027-12-12T18:25:34Z → 2027-12-13T16:08:48Z

  2. 02

    Kāla

    Pradoṣa is 2 muhūrtas after sunset: 17:42–19:28 on the 12th, 17:42–19:29 on the 13th.

    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 106 minutes on the 12th and 106 of 106 on the 13th.

    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 7800 s

  5. 05

    Ruling

    Dattātreyotpatti, Ujjain, 2027: Monday 13 December.

    confidence: determinate

Say it like this

In Ujjain, Dattātreyotpatti (Datta Jayanti) 2027 falls on Monday 13 December. Pūrṇimā runs from 23:56 on Sun 12 Dec to 21:39 on Mon 13 Dec and covers all of pradoṣa that evening.

ahargana.org/ujjain/festivals/2027/dattatreyotpatti · pac-rp@2026.1

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingMon 13 Dec
Ahargaṇa, classicalDisc centre, no refractionMon 13 Dec
compat-drikpanchangComparison profileMon 13 Dec
No institution has a recorded ruling for Ujjain.

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 12thCoveredSunset 13thCoveredRuled
Los Angeles10:26 → 08:0916:44113 min16:440 min12 Dec
Chicago12:26 → 10:0916:19119 min16:200 min12 Dec
Jersey City13:26 → 11:0916:29118 min16:290 min12 Dec
Port of Spain14:26 → 12:0917:45100 min17:450 min12 Dec
London18:26 → 16:0915:510 min15:5118 min13 Dec
Durban20:26 → 18:0918:500 min18:510 min12 Dec
Dubai22:26 → 20:0917:300 min17:30107 min13 Dec
Delhi23:56 → 21:3917:250 min17:25109 min13 Dec
Kolkata23:56 → 21:3916:530 min16:53106 min13 Dec
Singapore02:26 → 00:0918:590 min19:0096 min13 Dec
Sydney05:26 → 03:0919:590 min20:0077 min13 Dec
Suva06:26 → 04:0918:350 min18:3686 min13 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