Ruling · Rādhāṣṭamī · 1961

Monday 18 September

Boundaryin Tehran, under the Rashtriya Panchang method. A threshold is only 3 min 03 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 Sunday 17 September

Aṣṭamī is absent from madhyāhna. Not taken.

madhyāhna begins 11:35  12:23 madhyāhna ends
Aṣṭamī begins 12:25:40
10:4711:1111:3511:5912:2312:4713:11

0 of 48 minutes covered

Midday of Monday 18 September

Taken. Aṣṭamī reaches neither midday; the rule takes the second day.

madhyāhna begins 11:34  12:22 madhyāhna ends
Aṣṭamī ends 11:12:28
10:4611:1011:3411:5812:2212:4613:10

0 of 48 minutes covered

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

How it was decided

  1. 01

    Aṅga

    Aṣṭamī runs from 12:26 on Sun 17 Sep to 11:12 on Mon 18 Sep.

    1961-09-17T08:55:41Z → 1961-09-18T07:42:29Z

  2. 02

    Kāla

    Madhyāhna is 1 ghaṭikā either side of midday: 11:35–12:23 on the 17th, 11:34–12:22 on the 18th.

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

  3. 03

    Rule

    Aṣṭamī must be present during madhyāhna. It covers 0 of 48 minutes on the 17th and 0 of 48 on the 18th.

    Calendar Reform Committee 1955, General Rules for Religious Festivals, p. 103

  4. 04

    Tie-break

    Neither midday qualifies. The rule takes the second day.

    priority: unstated → second-day · margin 183 s < 300 s

  5. 05

    Ruling

    Rādhāṣṭamī, Tehran, 1961: Monday 18 September.

    confidence: boundary (margin)

Say it like this

In Tehran, Rādhāṣṭamī 1961 falls on Monday 18 September. Aṣṭamī runs from 12:26 on Sun 17 Sep to 11:12 on Mon 18 Sep, and reaches madhyāhna on neither day. It is 3 min 03 s from a threshold: treat the date as contested.

ahargana.org/tehran/festivals/1961/radhashtami · pac-rp@2026.1

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingMon 18 Sep
Ahargaṇa, classicalDisc centre, no refractionMon 18 Sep
compat-drikpanchangComparison profileSun 17 Sep
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/radhashtami · ruleset 2026.3-draft

Month
Bhādrapada, amānta
Pakṣa · aṅga
Śukla · Aṣṭamī
Kāla
Madhyāhna
Priority
Unstated
Tie-break
Longer coverage, as a boundary
Reference
CRC 1955, p. 103

“S 8 Durvastami (purvaviddha — S 8 of saura Bhadra except Bengal), Mahalaksmi vratarambha, Radhastami (madhyahna vyapini)” Calendar Reform Committee 1955, General Rules for Religious Festivals, p. 103.

The same rule, elsewhere

Twelve places, west to east. Local clock times.

PlaceAṣṭamīMadhyāhna 17thCoveredMadhyāhna 18thCoveredRuled
Los Angeles01:56 → 00:4212:2348 min12:230 min17 Sep
Chicago03:56 → 02:4212:2148 min12:200 min17 Sep
Jersey City04:56 → 03:4212:2648 min12:260 min17 Sep
Port of Spain04:56 → 03:4211:3648 min11:360 min17 Sep
London09:56 → 08:4212:3148 min12:300 min17 Sep
Durban10:56 → 09:4211:2748 min11:260 min17 Sep
Dubai12:56 → 11:4211:490 min11:490 min18 Sep
Delhi14:26 → 13:1211:510 min11:5148 min18 Sep
Kolkata14:26 → 13:1211:070 min11:0748 min18 Sep
Singapore16:26 → 15:1212:050 min12:0548 min18 Sep
Sydney18:56 → 17:4211:260 min11:2648 min18 Sep
Suva20:56 → 19:4211:370 min11:3748 min18 Sep
Profile · tradition
pac-rp@2026.1 · smarta
Rule
radhashtami@2026.3-draft
Engine · kernel
0.1.0 · de440 7eef…ea74
Boundary margin
300 s

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