1.
Coordinated Universal Time
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Coordinated Universal Time, abbreviated to UTC, is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean time at 0° longitude. It is one of closely related successors to Greenwich Mean Time. For most purposes, UTC is considered interchangeable with GMT, the first Coordinated Universal Time was informally adopted on 1 January 1960. This change also adopted leap seconds to simplify future adjustments, a number of proposals have been made to replace UTC with a new system that would eliminate leap seconds, but no consensus has yet been reached. Leap seconds are inserted as necessary to keep UTC within 0.9 seconds of universal time, see the Current number of leap seconds section for the number of leap seconds inserted to date. The official abbreviation for Coordinated Universal Time is UTC and this abbreviation arose from a desire by the International Telecommunication Union and the International Astronomical Union to use the same abbreviation in all languages. English speakers originally proposed CUT, while French speakers proposed TUC, the compromise that emerged was UTC, which conforms to the pattern for the abbreviations of the variants of Universal Time. Time zones around the world are expressed using positive or negative offsets from UTC, the westernmost time zone uses UTC−12, being twelve hours behind UTC, the easternmost time zone, theoretically, uses UTC+12, being twelve hours ahead of UTC. In 1995, the nation of Kiribati moved those of its atolls in the Line Islands from UTC-10 to UTC+14 so that the country would all be on the same day. UTC is used in internet and World Wide Web standards. The Network Time Protocol, designed to synchronise the clocks of computers over the internet, computer servers, online services and other entities that rely on having a universally accepted time use UTC as it is more specific than GMT. If only limited precision is needed, clients can obtain the current UTC from a number of official internet UTC servers, for sub-microsecond precision, clients can obtain the time from satellite signals. UTC is also the standard used in aviation, e. g. for flight plans. Weather forecasts and maps all use UTC to avoid confusion about time zones, the International Space Station also uses UTC as a time standard. Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up by many time zones, UTC is also used in digital tachographs used on large goods vehicles under EU and AETR rules. UTC divides time into days, hours, minutes and seconds, days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 60 minutes, the number of seconds in a minute is usually 60, but with an occasional leap second, it may be 61 or 59 instead
2.
Time in Europe
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Europe spans 7 primary time zones, excluding summer time offsets. Most European countries use summer time and harmonise their summer time adjustments, see Summer time in Europe for details. The time zones actually in use in Europe differ significantly from their pure theoretical variants as used for example under the time system. Theoretically the world is divided into 24 time zones of 15 degrees, however, due to geographical and cultural factors it is not practical to divide the world so evenly and actual time zones may differ significantly from their theoretical borders. In Europes case, the use of the Central European Time Zone causes a major distortion in some areas from the theoretical time or the solar time. CET is theoretically centred on 15°E, however, Spain lying almost entirely in the Western hemisphere, and France with some regions to the west should theoretically use UTC, as they did before the Second World War. The general result is a solar noon which is later than clock noon. This results in later sunrises and sunsets than should theoretically happen, the Benelux countries should also theoretically use GMT. Russia and Belarus have observed permanent summer time between March 2011 and October 2014, since October 2014 Russia observed permanent winter time. Iceland can be considered to be on de facto permanent summer time because, since 1968, it uses UTC time all year, despite being located more than 15° west of the prime meridian. It should therefore be located in UTC-1, but chooses to remain closer to continental European time, of the 28 EU member states,3 use Western European Time and 8 use Eastern European Time. The other 17 member states all use Central European Time, norway, Switzerland, Serbia, Kosovo, Macedonia, Montenegro, San Marino, Vatican City, Andorra, Monaco and Liechtenstein also observe the Central European Time. Northern Cyprus and Transnistria observe the Eastern European Time, azores, in Portugal, observes the Atlantic/Azores Time and the Canary Islands, in Spain, observes the Western European Time. Moldova, Belarus and Ukraine observe the Eastern European Time
3.
Western European Time
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Western European Time is a time zone covering parts of western and northwestern Europe. WEST is called British Summer Time in the UK and is known as Irish Standard Time in Ireland. Conversely, Iceland and eastern Greenland are included although both are west of 7. 5°W, in September 2013, a Spanish parliamentary committee recommended switching to WET, a move being considered by MPs. However, the German occupation switched France to German time, two other occupied territories, Belgium and the Netherlands, did the same, and Spain also switched to CET in solidarity with Germany under the orders of General Franco. In the United Kingdom, from 1940 to 1945 British Summer Time was used in winters, between 18 February 1968 and 31 October 1971, BST was used all year round. In Ireland, from 1940 to 1946 Irish Summer Time was used all year round, between 18 February 1968 and 31 October 1971, Irish Standard Time was used all year round. In Portugal, CET was used in the mainland from 1966 to 1976, the autonomous region of the Azores used WET from 1992 to 1993. Iceland Mykines, Faroe Islands Western Ireland Western Portugal Madeira Canary Islands These areas are located between 7°30′ W and 22°30′ W Areas using UTC+1, See Central European Time
4.
Greenwich Mean Time
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Greenwich Mean Time is the mean solar time at the Royal Observatory in Greenwich, London. GMT was formerly used as the civil time standard, now superseded in that function by Coordinated Universal Time. Today GMT is considered equivalent to UTC for UK civil purposes and for navigation is considered equivalent to UT1, consequently, the term GMT should not be used for precise purposes. Due to Earths uneven speed in its orbit and its axial tilt, noon GMT is rarely the exact moment the sun crosses the Greenwich meridian. This event may occur up to 16 minutes before or after noon GMT, noon GMT is the annual average moment of this event, which accounts for the word mean in Greenwich Mean Time. Originally, astronomers considered a GMT day to start at noon while for almost everyone else it started at midnight, to avoid confusion, the name Universal Time was introduced to denote GMT as counted from midnight. Astronomers preferred the old convention to simplify their observational data, so each night was logged under a single calendar date. Today Universal Time usually refers to UTC or UT1, in some countries Greenwich Mean Time is the legal time in the winter and the population uses the term. For an explanation of why this is, see GMT in legislation below, synchronisation of the chronometer on GMT did not affect shipboard time, which was still solar time. Most time zones were based upon GMT, as an offset of a number of hours ahead of GMT or behind GMT and it was gradually adopted for other purposes, but a legal case in 1858 held local mean time to be the official time. On 14 May 1880, a signed by Clerk to Justices appeared in The Times, stating that Greenwich time is now kept almost throughout England. For example, our polling booths were opened, say, at 813 and closed at 413 PM. This was changed later in 1880, GMT was adopted on the Isle of Man in 1883, Jersey in 1898 and Guernsey in 1913. Ireland adopted GMT in 1916, supplanting Dublin Mean Time, hourly time signals from Greenwich Observatory were first broadcast on 5 February 1924, rendering the time ball at the observatory redundant in the process. The daily rotation of the Earth is irregular and constantly slows, on 1 January 1972, GMT was superseded as the international civil time standard by Coordinated Universal Time, maintained by an ensemble of atomic clocks around the world. Indeed, even the Greenwich meridian itself is not quite what it used to be—defined by the centre of the instrument at the Observatory at Greenwich. Nevertheless, the line in the old observatorys courtyard today differs no more than a few metres from that line which is now the prime meridian of the world. Historically GMT has been used two different conventions for numbering hours. The long-standing astronomical convention dating from the work of Ptolemy, was to refer to noon as zero hours and this contrasted with the civil convention of referring to midnight as zero hours dating from the Romans
5.
Western European Summer Time
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Western European Summer Time is a summer daylight saving time scheme,1 hour ahead of Coordinated Universal Time. Also sometimes erroneously referred to as Irish Summer Time, the scheme runs from the last Sunday in March to the last Sunday in October each year. At both the start and end of the schemes, clock changes take place at 01,00 UTC, during the winter, Greenwich Mean Time is used. The asymmetry reflects temperature more than the length of daylight, Ireland observes Standard Time during the summer months and changes to UTC+0 in winter. As Irelands winter time period begins on the last Sunday in October and finishes on the last Sunday in March, the result is the same as if it observed summer time. The following countries and territories use Western European Summer Time during the summer, starting in 1916, the dates for the beginning and end of BST each year were mandated by the Parliament of the United Kingdom. In February 2002, the Summer Time Order 2002 changed the dates and times to match European rules for moving to, note, Until 1 October 1916 time in all of Ireland was based on Dublin Mean Time, GMT −25 minutes. BBC News report, Tundra time call in clocks debate, UK Government Report, Overview of the pros and cons of British Summer Time
6.
Time in the Republic of Ireland
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Ireland uses Irish Standard Time in the summer months and Greenwich Mean Time in the winter period. In Ireland, the Standard Time Act 1968 legally established that the time for purposes in the State shall be one hour in advance of Greenwich mean time throughout the year. This act was amended by the Standard Time Act 1971, which legally established Greenwich Mean Time as a time period. Ireland therefore operates one hour behind standard time during the winter period and this is defined in contrast to the other states in the European Union, which operate one hour ahead of standard time during the summer period, but produces the same end result. The instant of transition to and from saving time is synchronised across Europe. In Ireland, Winter time begins at 02,00 IST on the last Sunday in October, the Statutes Act,1880 defined Dublin Mean Time as the legal time for Ireland. T. M. Healy opposed the reading on the basis that while the Daylight Saving Bill added to the length of your daylight. After the Irish Free State became independent in 1922, subsequent developments tended to mirror those in the United Kingdom and this avoided having different times on either side of the border with Northern Ireland. Summer time was provided on a basis by acts in 1923 and 1924. The 1925 act provided a summer time period, which could be varied by ministerial order. Double summer time was considered but not introduced during the Emergency of World War II, from 1968 standard time was observed all year round, with no winter time change. This was an experiment in the run-up to Irelands 1973 accession to the EEC, in those years, time in Ireland was the same as in the six EEC countries, except in the summer in Italy, which switched to Central European Summer Time. From the 1980s, the dates of switch between winter and summer time have been synchronised across the European Union. The statutory instruments that have been issued under the Standard Time Acts are listed below, in format year/SI-number, except where stated, those issued up to 1967 were called Summer Time Order <year>, while those issued from 1981 are Winter Time Order <year>. In November 2012, Tommy Broughan introduced a members bill to permit a three-year trial of advancing time by one hour, to CET in winter. In July 2014, the joint committee issued an invitation for submissions on the bill, closing time in Irish public houses was half an hour later during summer time. In 2000, the closing hours were simplified by removing summer/winter time changes. Between 1933 and 1961, lighting-up time was an hour before/after sunrise/sunset in summer-time, since 1961, it has been half-an-hour in all cases
7.
Central European Summer Time
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It corresponds to UTC + two hours. Other names which have been applied to Central European Summer Time are Middle European Summer Time, Central European Daylight Saving Time, and Bravo Time. Since 1996 European Summer Time has been observed between 1,00 UTC on the last Sunday of March and 1,00 on the last Sunday of October, the following countries and territories use Central European Summer Time. In addition, Libya used CEST during the years 1951–1959, 1982–1989, 1996–1997, European Summer Time Other countries and territories in UTC+2 time zone Other names of UTC+2 time zone
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Belarus since 2011-03-27[4]
Russia: Moscow Time since 2014-10-26, including all railroad time in Russia, including railroads in Kaliningrad Oblast
Turkey since 2016-09-07
Comoros
Djibouti
Eritrea
Ethiopia
Kenya
Madagascar
Mayotte
Scattered Islands in the Indian Ocean
Somalia
South Sudan
Tanzania
Uganda
