Ruling · Śaṅkara Jayantī · 2021

Monday 17 May

Boundaryin Datong, under the Rashtriya Panchang method. Both middays qualify and the rule does not say which to take. Say “contested”.

Decide it for

DatongDelhiKolkataSingaporeSydneyJersey City

40°06′ N 113°17′ E · Asia/Shanghai · GeoNames 2037799

The two middays

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

Midday of Sunday 16 May

Qualifies with 16 of 48 minutes. Not taken.

madhyāhna begins 11:59  12:47 madhyāhna ends
Pañcamī begins 12:31:31
11:1111:3511:5912:2312:4713:1113:35

16 of 48 minutes covered, the last 16

Midday of Monday 17 May

Taken. Both middays qualify; the rule is silent, and this one is covered longer.

madhyāhna begins 12:00  12:48 madhyāhna ends
11:1211:3612:0012:2412:4813:1213:36

48 of 48 minutes covered

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

How it was decided

  1. 01

    Aṅga

    Pañcamī runs from 12:32 on Sun 16 May to 14:05 on Mon 17 May.

    2021-05-16T04:31:31Z → 2021-05-17T06:05:04Z

  2. 02

    Kāla

    Madhyāhna is 1 ghaṭikā either side of midday: 11:59–12:47 on the 16th, 12:00–12:48 on the 17th.

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

  3. 03

    Rule

    Pañcamī must be present during madhyāhna. It covers 16 of 48 minutes on the 16th and 48 of 48 on the 17th.

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

  4. 04

    Tie-break

    Both middays qualify and the rule marks neither. The one covered longer is ruled, as a boundary.

    priority: unstated → greater-coverage · margin 958 s

  5. 05

    Ruling

    Śaṅkara Jayantī, Datong, 2021: Monday 17 May.

    confidence: boundary (tie-break-unstated)

Say it like this

In Datong, Śaṅkara Jayantī 2021 falls on Monday 17 May. Pañcamī runs from 12:32 on Sun 16 May to 14:05 on Mon 17 May and covers all of madhyāhna that midday. It also reaches the previous midday for 16 minutes; the rule does not say which to take, and the one covered longer is ruled: treat the date as contested.

ahargana.org/datong/festivals/2021/shankara-jayanti · pac-rp@2026.1

Who says what

AuthorityKindDate
Ahargaṇa, pac-rpThis rulingMon 17 May
Ahargaṇa, classicalDisc centre, no refractionMon 17 May
compat-drikpanchangComparison profileMon 17 May
No institution has a recorded ruling for Datong.

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

The rule, as data

/rules/shankara-jayanti · ruleset 2026.3-draft

Month
Vaiśākha, amānta
Pakṣa · aṅga
Śukla · Pañcamī
Kāla
Madhyāhna
Priority
Unstated
Tie-break
Longer coverage, as a boundary
Reference
CRC 1955, p. 102

“S 5 Sankara jayanti.” Calendar Reform Committee 1955, General Rules for Religious Festivals, p. 102.

The same rule, elsewhere

Twelve places, west to east. Local clock times.

PlacePañcamīMadhyāhna 16thCoveredMadhyāhna 17thCoveredRuled
Los Angeles21:32 → 23:0512:2648 min12:260 min16 May
Chicago23:32 → 01:0512:2348 min12:230 min16 May
Jersey City00:32 → 02:0512:2948 min12:290 min16 May
Port of Spain00:32 → 02:0511:3948 min11:390 min16 May
London05:32 → 07:0512:3348 min12:330 min16 May
Durban06:32 → 08:0511:2848 min11:280 min16 May
Dubai08:32 → 10:0511:5148 min11:510 min16 May
Delhi10:02 → 11:3511:5448 min11:540 min16 May
Kolkata10:02 → 11:3511:0948 min11:0926 min16 May
Singapore12:32 → 14:0512:3748 min12:3748 min16 May
Sydney14:32 → 16:0511:270 min11:2748 min17 May
Suva16:32 → 18:0511:390 min11:3948 min17 May
Profile · tradition
pac-rp@2026.1 · smarta
Rule
shankara-jayanti@2026.3-draft
Engine · kernel
0.1.0 · de440 7eef…ea74
Boundary margin
300 s

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