Atlantic Standard Time: Wikis

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Updated live from Wikipedia, last check: May 29, 2012 22:52 UTC (42 seconds ago)

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AST is UTC-4

The Atlantic Standard Time Zone (AST) is a geographical region that keeps time by subtracting four hours from either Coordinated Universal Time (UTC) or Greenwich Mean Time (GMT), resulting in UTC-4 or GMT-4. The clock time in this zone is based on the mean solar time of the 60th meridian west of the Greenwich Observatory.

In Canada, the provinces of New Brunswick^[1] and Nova Scotia^[2] reckon time specifically as an offset of 4 hours from Greenwich Mean time (GMT-4). (UTC is regularly adjusted by means of leap seconds to keep it synchronized to within 1 second of GMT.) Prince Edward Island and small portions of Quebec (eastern Côte-Nord and the Magdalen Islands) are also part of the Atlantic Standard Time Zone. Officially, the entirety of Newfoundland and Labrador observes Newfoundland Standard Time,^[3] but in practice most of Labrador uses the Atlantic Standard Time Zone.

Other parts of the world that keep time by subtracting four hours from UTC include Bermuda, in the North Atlantic; many Caribbean islands, including Puerto Rico, the US Virgin Islands; and several South American countries, such as Paraguay, Chile, Bolivia, and parts of Brazil. Venezuela used AST until December 9, 2007, when it switched to UTC-4:30.

AST is known (where applicable) as Atlantic Daylight Time (ADT) during daylight saving time, and has one hour added to make it three hours behind GMT (UTC-3).

Major metropolitan areas

Time zones in North America
Time Zone	UTC-10	UTC-9	UTC-8	UTC-7	UTC-6	UTC-5	UTC-4	UTC-3:30	UTC-3	UTC-2:30	UTC-2
Name	Hawaii-Aleutian Standard	Alaska Standard	Pacific Standard	Mountain Standard	Central Standard	Eastern Standard	Atlantic Standard	Newfoundland Standard	Saint Pierre and Miquelon Standard
Name		Hawaii-Aleutian Daylight	Alaska Daylight	Pacific Daylight	Mountain Daylight	Central Daylight	Eastern Daylight		Atlantic Daylight	Newfoundland Daylight	Saint Pierre and Miquelon Daylight

Sources

Time offsets from Coordinated Universal Time (UTC)

−12 · −11 · −10 · −9:30 · −9 · −8 · −7 · −6 · −5 · −4:30 · −4 · −3:30 · −3 · −2:30 · −2 · −1 · −0:44 · −0:25 · UTC (0) · +0:20 · +0:30 · +1 · +2 · +3 · +3:30 · +4 · +4:30 · +4:51 · +5 · +5:30 · +5:40 · +5:45 · +6 · +6:30 · +7 · +7:20 · +7:30 · +8 · +8:30 · +8:45 · +9 · +9:30 · +10 · +10:30 · +11 · +11:30 · +12 · +12:45 · +13 · +13:45 · +14

Daylight saving time (DST) · Northern Hemisphere · Southern Hemisphere · Historical Only