Ruling · Rādhāṣṭamī · 2083

Saturday 18 September

Boundaryin Tehran, under the Rashtriya Panchang method. A threshold is only 2 min 30 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 Saturday 18 September

Taken. The only midday Aṣṭamī reaches.

madhyāhna begins 11:34  12:22 madhyāhna ends
Aṣṭamī begins 11:31:56
10:4611:1011:3411:5812:2212:4613:10

48 of 48 minutes covered

Midday of Sunday 19 September

Aṣṭamī is absent from madhyāhna. Not taken.

madhyāhna begins 11:34  12:22 madhyāhna ends
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 11:32 on Sat 18 Sep to 09:27 on Sun 19 Sep.

    2083-09-18T08:01:57Z → 2083-09-19T05:57:09Z

  2. 02

    Kāla

    Madhyāhna is 1 ghaṭikā either side of midday: 11:34–12:22 on the 18th, 11:34–12:22 on the 19th.

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

  3. 03

    Rule

    Aṣṭamī must be present during madhyāhna. It covers 48 of 48 minutes on the 18th and 0 of 48 on the 19th.

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

  4. 04

    Tie-break

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

    priority: unstated → only-day · margin 150 s < 300 s

  5. 05

    Ruling

    Rādhāṣṭamī, Tehran, 2083: Saturday 18 September.

    confidence: boundary (margin)

Say it like this

In Tehran, Rādhāṣṭamī 2083 falls on Saturday 18 September. Aṣṭamī runs from 11:32 on Sat 18 Sep to 09:27 on Sun 19 Sep and covers all of madhyāhna that midday. It is 2 min 30 s from a threshold: treat the date as contested.

ahargana.org/tehran/festivals/2083/radhashtami · pac-rp@2026.1

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingSat 18 Sep
Ahargaṇa, classicalDisc centre, no refractionSat 18 Sep
compat-drikpanchangComparison profileSat 18 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 18thCoveredMadhyāhna 19thCoveredRuled
Los Angeles01:02 → 22:5712:2348 min12:230 min18 Sep
Chicago03:02 → 00:5712:2148 min12:200 min18 Sep
Jersey City04:02 → 01:5712:2648 min12:260 min18 Sep
Port of Spain04:02 → 01:5711:3648 min11:360 min18 Sep
London09:02 → 06:5712:3048 min12:300 min18 Sep
Durban10:02 → 07:5711:2648 min11:260 min18 Sep
Dubai12:02 → 09:5711:4935 min11:490 min18 Sep
Delhi13:32 → 11:2711:510 min11:510 min19 Sep
Kolkata13:32 → 11:2711:070 min11:0621 min19 Sep
Singapore16:02 → 13:5712:350 min12:3548 min19 Sep
Sydney18:02 → 15:5711:260 min11:2648 min19 Sep
Suva20:02 → 17:5711:370 min11:3748 min19 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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