Ruling · Guru Pūrṇimā · 1997

Sunday 20 July

Boundaryin Daqing, under the Rashtriya Panchang method. A threshold is only 1 min 42 s away. Say “contested”.

Decide it for

DaqingDelhiKolkataSingaporeSydneyJersey City

46°35′ N 125°00′ E · Asia/Shanghai · GeoNames 2037860

The two middays

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

Midday of Saturday 19 July

Pūrṇimā is absent from madhyāhna. Not taken.

madhyāhna begins 11:22  12:10 madhyāhna ends
10:3410:5811:2211:4612:1012:3412:58

0 of 48 minutes covered

Midday of Sunday 20 July

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

madhyāhna begins 11:22  12:10 madhyāhna ends
Pūrṇimā ends 11:20:16
10:3410:5811:2211:4612:1012:3412:58

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 14:15 on Sat 19 Jul to 11:20 on Sun 20 Jul.

    1997-07-19T06:15:25Z → 1997-07-20T03:20:17Z

  2. 02

    Kāla

    Madhyāhna is 1 ghaṭikā either side of midday: 11:22–12:10 on the 19th, 11:22–12:10 on the 20th.

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

  3. 03

    Rule

    Pūrṇimā must be present during madhyāhna. It covers 0 of 48 minutes on the 19th and 0 of 48 on the 20th.

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

  4. 04

    Tie-break

    Neither midday qualifies. The rule takes the second day.

    priority: paraviddha → second-day · margin 102 s < 300 s

  5. 05

    Ruling

    Guru Pūrṇimā, Daqing, 1997: Sunday 20 July.

    confidence: boundary (margin)

Say it like this

In Daqing, Guru Pūrṇimā 1997 falls on Sunday 20 July. Pūrṇimā runs from 14:15 on Sat 19 Jul to 11:20 on Sun 20 Jul, and reaches madhyāhna on neither day. It is 1 min 42 s from a threshold: treat the date as contested.

ahargana.org/daqing/festivals/1997/guru-purnima · pac-rp@2026.1

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingSun 20 Jul
Ahargaṇa, classicalDisc centre, no refractionSun 20 Jul
compat-drikpanchangComparison profileSun 20 Jul
No institution has a recorded ruling for Daqing.

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

The rule, as data

/rules/guru-purnima · ruleset 2026.3-draft

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

“S 15 Guru purnima (paraviddha), Vyasa puja (paraviddha, 3 muhurtas after sunrise), Kokila vrata (sayahna vyapini). Siva sayanotsava (pradosavyapini).” Calendar Reform Committee 1955, General Rules for Religious Festivals, p. 102.

The same rule, elsewhere

Twelve places, west to east. Local clock times.

PlacePūrṇimāMadhyāhna 19thCoveredMadhyāhna 20thCoveredRuled
Los Angeles23:15 → 20:2012:3548 min12:350 min19 Jul
Chicago01:15 → 22:2012:3348 min12:330 min19 Jul
Jersey City02:15 → 23:2012:3848 min12:380 min19 Jul
Port of Spain02:15 → 23:2011:4848 min11:480 min19 Jul
London07:15 → 04:2012:4248 min12:420 min19 Jul
Durban08:15 → 05:2011:3848 min11:380 min19 Jul
Dubai10:15 → 07:2012:0148 min12:010 min19 Jul
Delhi11:45 → 08:5012:0348 min12:030 min19 Jul
Kolkata11:45 → 08:5011:1921 min11:190 min19 Jul
Singapore14:15 → 11:2012:470 min12:470 min20 Jul
Sydney16:15 → 13:2011:380 min11:3848 min20 Jul
Suva18:15 → 15:2011:490 min11:4948 min20 Jul
Profile · tradition
pac-rp@2026.1 · smarta
Rule
guru-purnima@2026.3-draft
Engine · kernel
0.1.0 · de440 7eef…ea74
Boundary margin
300 s

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