Ruling · Caitrī Pūrṇimā · 1921

Thursday 21 April

Boundaryin Tehran, under the Rashtriya Panchang method. A threshold is only 3 min 17 s away. Say “contested”.

Decide it for

TehranDelhiKolkataSingaporeSydneyJersey City

35°42′ N 51°25′ E · Asia/Tehran · GeoNames 112931

The two middays

One ghaṭī is 24 minutes. Madhyāhna is 1 ghaṭikā either side of midday.

Midday of Thursday 21 April

Taken. The only midday Pūrṇimā reaches.

madhyāhna begins 11:34  12:22 madhyāhna ends
Pūrṇimā begins 12:19:50
10:4611:1011:3411:5812:2212:4613:10

3 of 48 minutes covered, the last 3

Midday of Friday 22 April

Pūrṇimā is absent from madhyāhna. Not taken.

madhyāhna begins 11:34  12:22 madhyāhna ends
Pūrṇimā ends 11:14:42
10:4611:1011:3411:5812:2212:4613:10

0 of 48 minutes covered

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

How it was decided

  1. 01

    Aṅga

    Pūrṇimā runs from 12:19 on Thu 21 Apr to 11:14 on Fri 22 Apr.

    1921-04-21T08:54:06Z → 1921-04-22T07:48:58Z

  2. 02

    Kāla

    Madhyāhna is 1 ghaṭikā either side of midday: 11:34–12:22 on the 21st, 11:34–12:22 on the 22nd.

    madhyahna: midday-pm-1-ghatika · sunrise and sunset: upper limb, 31′ + 16′

  3. 03

    Rule

    Pūrṇimā must be present during madhyāhna. It covers 3 of 48 minutes on the 21st and 0 of 48 on the 22nd.

    Calendar Reform Committee 1955, General Rules for Religious Festivals, p. 102

  4. 04

    Tie-break

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

    priority: paraviddha → only-day · margin 197 s < 300 s

  5. 05

    Ruling

    Caitrī Pūrṇimā, Tehran, 1921: Thursday 21 April.

    confidence: boundary (margin)

Say it like this

In Tehran, Caitrī Pūrṇimā 1921 falls on Thursday 21 April. Pūrṇimā runs from 12:19 on Thu 21 Apr to 11:14 on Fri 22 Apr and covers 3 of 48 minutes of madhyāhna that midday. It is 3 min 17 s from a threshold: treat the date as contested.

ahargana.org/tehran/festivals/1921/chaitri-purnima · pac-rp@2026.1

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingThu 21 Apr
Ahargaṇa, classicalDisc centre, no refractionThu 21 Apr
compat-drikpanchangComparison profileFri 22 Apr
No institution has a recorded ruling for Tehran.

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

The rule, as data

/rules/chaitri-purnima · ruleset 2026.3-draft

Month
Caitra, amānta
Pakṣa · aṅga
Śukla · Pūrṇimā
Kāla
Madhyāhna
Priority
Paraviddhā
Tie-break
Second day
Reference
CRC 1955, p. 102

“S 15 Caitri purnima (paraviddha), Hanumat jayanti, Oli ending (Jain).” Calendar Reform Committee 1955, General Rules for Religious Festivals, p. 102.

The same rule, elsewhere

Twelve places, west to east. Local clock times.

PlacePūrṇimāMadhyāhna 21stCoveredMadhyāhna 22ndCoveredRuled
Los Angeles00:54 → 23:4911:2848 min11:280 min21 Apr
Chicago03:54 → 02:4912:2648 min12:250 min21 Apr
Jersey City03:54 → 02:4911:3148 min11:310 min21 Apr
Port of Spain04:54 → 03:4911:4148 min11:410 min21 Apr
London09:54 → 08:4912:3648 min12:360 min21 Apr
Durban10:54 → 09:4911:3048 min11:300 min21 Apr
Dubai12:54 → 11:4911:540 min11:540 min22 Apr
Delhi14:24 → 13:1911:560 min11:5648 min22 Apr
Kolkata14:24 → 13:1911:120 min11:1148 min22 Apr
Singapore15:54 → 14:4911:390 min11:3948 min22 Apr
Sydney18:54 → 17:4911:300 min11:3048 min22 Apr
Suva20:54 → 19:4911:410 min11:4148 min22 Apr
Profile · tradition
pac-rp@2026.1 · smarta
Rule
chaitri-purnima@2026.3-draft
Engine · kernel
0.1.0 · de440 7eef…ea74
Boundary margin
300 s

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