Pacific/Bougainville

Time zone identifier: Pacific/Bougainville

Current civil offset: +11:00 (+11)

Current DST state: Observing Standard Time

First standard time adoption: Adopted on 1879-12-31

Local Mean Time (LMT): +10:22:16 based on geographic meridian

Total recorded transitions: 5 transitions across 5 distinct offsets

Associated countries: PG

Historical Offset Step Chart (1880 to Present)

Text summary: Pacific/Bougainville shifted between 5 distinct offsets from 1879-12-31 through the modern era.

Complete Transition History (5 Transitions)

UTC Instant	Local Wall Time	Shift	Abbreviation	DST	Effect
`1879-12-31T13:37:44Z`	`1879-12-31 23:26:16`	+10:22:16 → +09:48:32	`PMMT`	No	overlap
`1894-12-31T14:11:28Z`	`1895-01-01 00:11:28`	+09:48:32 → +10:00	`+10`	No	gap
`1942-06-30T14:00:00Z`	`1942-06-30 23:00:00`	+10:00 → +09:00	`+09`	No	overlap
`1945-08-20T15:00:00Z`	`1945-08-21 01:00:00`	+09:00 → +10:00	`+10`	No	gap
`2014-12-27T16:00:00Z`	`2014-12-28 03:00:00`	+10:00 → +11:00	`+11`	No	gap

Notes from the Maintainers

Source: australasia (Lines 680 to 697)

From Paul Eggert (2014-10-13):
Base the Bougainville entry on the Arawa-Kieta region, which appears to have
the most people even though it was devastated in the Bougainville Civil War.

Although Shanks gives 1942-03-15 / 1943-11-01 for UT +09, these dates
are apparently rough guesswork from the starts of military campaigns.
The World War II entries below are instead based on Arawa-Kieta.
The Japanese occupied Kieta in July 1942,
according to the Pacific War Online Encyclopedia
https://pwencycl.kgbudge.com/B/o/Bougainville.htm
and seem to have controlled it until their 1945-08-21 surrender.

The Autonomous Region of Bougainville switched from UT +10 to +11
on 2014-12-28 at 02:00.  They call +11 "Bougainville Standard Time".
See:
http://www.bougainville24.com/bougainville-issues/bougainville-gets-own-timezone/

Attributed Statements:

Paul Eggert (2014-10-13):

Base the Bougainville entry on the Arawa-Kieta region, which appears to have the most people even though it was devastated in the Bougainville Civil War. Although Shanks gives 1942-03-15 / 1943-11-01 for UT +09, these dates are apparently rough guesswork from the starts of military campaigns. The World War II entries below are instead based on Arawa-Kieta. The Japanese occupied Kieta in July 1942, according to the Pacific War Online Encyclopedia https://pwencycl.kgbudge.com/B/o/Bougainville.htm and seem to have controlled it until their 1945-08-21 surrender. The Autonomous Region of Bougainville switched from UT +10 to +11 on 2014-12-28 at 02:00. They call +11 "Bougainville Standard Time". See: http://www.bougainville24.com/bougainville-issues/bougainville-gets-own-timezone/

Methodology Note: The 1970 Rule

tzdb guarantees accuracy for timestamps from 1970 onwards. Transitions prior to 1970 represent best-effort historical reconstructions.