The name Coordinated Universal Time was officially adopted in 1967.Why UTC – not CUT or TUC?UTC was adjusted several times until 1972, when leap seconds were introduced to keep UTC in line with the Earth's rotation, which is not entirely even, and less exact than atomic clocks. Decisions to introduce a leap second are announced at least six months in advance in "Bulletin C" produced by the International Earth Rotation and Reference Systems Service. [27] In 1928, the term Universal Time (UT) was introduced by the International Astronomical Union to refer to GMT, with the day starting at midnight. [21] This ensures that all pilots, regardless of location, are using the same 24-hour clock, thus avoiding confusion when flying between time zones. Leap seconds are timed to keep DUT1 within the vertical range depicted by this graph. [10], UTC divides time into days, hours, minutes and seconds. All Rights Reserved. Time zones around the world are expressed using positive or negative offsets from UTC, as in the list of time zones by UTC offset. Coordinated Universal Time (UTC) has considerably changed in recent years. Copyright © 2021 CJKI. [23], UTC does not change with a change of seasons, but local time or civil time may change if a time zone jurisdiction observes daylight saving time (summer time). [19] (See the article on International Atomic Time for details.). [22] See the list of military time zones for letters used in addition to Z in qualifying time zones other than Greenwich. [4] Leap seconds are inserted as necessary to keep UTC within 0.9 second of the UT1 variant of universal time. [1], The system has been adjusted several times, including a brief period during which the time-coordination radio signals broadcast both UTC and "Stepped Atomic Time (SAT)" before a new UTC was adopted in 1970 and implemented in 1972. For the album by Caspar Brötzmann and Page Hamilton, see, International Earth Rotation and Reference Systems Service, International Bureau of Weights and Measures, "Coordinated Universal Time (UTC) to retain "leap second, National Institute of Standards and Technology 2012, National Institute of Standards and Technology 2011, International Earth Rotation and Reference Systems Service 2011, Military & Civilian Time Designations n.d, "ITU World Radiocommunication Conference set for Geneva, 2–27 November 2015", "Coordinated Universal Time (UTC) to retain 'leap second, "UTC might be redefined without Leap Seconds", "Wait a second... 2015 will be a little longer", "IAU resolutions adopted at the XVIth General Assembly, Grenoble, France, 1976", "Scientists propose 'leap hour' to fix time system", "Standard-frequency and time-signal emissions", "A Few Facts Concerning GMT, UT, and the RGO", "Frequency of caesium in terms of Ephemeris Time", "Time-reckoning for the twentieth century", "Note on Coordinated Universal Time (CCTF/09-32)", National Institute of Standards and Technology, "NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB", "The leap second: its history and possible future", "Time scales, their users, and leap seconds", "TF.460-4: Standard-frequency and time-signal emissions", Definition of Coordinated Universal Time in German law–ZeitG §1 (3), International Earth Rotation Service; list of differences between TAI and UTC from 1961 to present, W3C Specification about UTC Date and Time, Standard of time definition: UTC, GPS, LORAN and TAI, What is in a name? Time zones are usually defined as differing from UTC by an integer number of hours,[20] although the laws of each jurisdiction would have to be consulted if sub-second accuracy was required. Some time in the 22nd century, two leap seconds will be required every year. Nearly all UTC days contain exactly 86,400 SI seconds with exactly 60 seconds in each minute. Copyright(C)2002-2021 National Institute of Information and Communications Technology. The current use of only the leap second opportunities in June and December will be insufficient to maintain a difference of less than 1 second, and it might be decided to introduce leap seconds in March and September. UTC is within about one second of mean solar time at 0° longitude,[15] so that, because the mean solar day is slightly longer than 86,400 SI seconds, occasionally the last minute of a UTC day is adjusted to have 61 seconds. È stato stabilito dall'Unione internazionale delle telecomunicazioni. The length of the SI second was calibrated on the basis of the second of ephemeris time[32][35] and can now be seen to have a relationship with the mean solar day observed between 1750 and 1892, analysed by Simon Newcomb. The compromise that emerged was UTC,[6] which conforms to the pattern for the abbreviations of the variants of Universal Time (UT0, UT1, UT2, UT1R, etc.).[7]. For example, local time on the east coast of the United States is five hours behind UTC during winter, but four hours behind while daylight saving is observed there.[24]. UTC is also the time standard used in aviation,[9] e.g. The extra second is called a leap second. It was thought better for time signals to maintain a consistent frequency, and that this frequency should match the SI second. . It is also known as "Z time" or "Zulu Time". Coordinated Universal Time (abbreviated to UTC) is the primary time standard by which the world regulates clocks and time. 今、標準時として使っている時間 が「Coordinated Universal Time （コーディネーテッド・ユニバーサル・タイム） 」です。 The Scottish-Canadian engineer Sir Sandford Fleming promoted worldwide standard time zones, a prime meridian, and the use of the 24-hour clock as key elements in communicating the accurate time. This publication allowed a value to be chosen for the length of the atomic second that would accord with the celestial laws of motion. Since 1972, UTC is calculated by subtracting the accumulated leap seconds from International Atomic Time (TAI), which is a coordinate time scale tracking notional proper time on the rotating surface of the Earth (the geoid). Coordinated Universal Time (UTC), UTC +0 The IANA time zone identifier for UTC is UTC. Copyright (C) 1994- Nichigai Associates, Inc., All rights reserved. This change also adopted leap seconds to simplify future adjustments. [47] The resulting gradual shift of the sun's movements relative to civil time is analogous to the shift of seasons relative to the yearly calendar that results from the calendar year not precisely matching the tropical year length. For other uses, see, This article is about the time standard abbreviated as "UTC". ãƒ»æ°´è³‡æºç”¨èªžé›†ã§ã®ã€ŒCoordinated Universal Time」の意味, JST科学技術用語日英対訳辞書での「Coordinated Universal Time」の意味, 英和GIS用語集での「Coordinated Universal Time」の意味, 日本語WordNet(英和)での「Coordinated Universal Time」の意味, 「coordinated universal time」に関する類語一覧, EDR日英対訳辞書での「Coordinated Universal Time」の意味, 日英・英日専門用語辞書での「Coordinated Universal Time」の意味, クロスランゲージ 37分野専門語辞書での「Coordinated Universal Time」の意味, Weblio英和対訳辞書での「Coordinated Universal Time」の意味, Wiktionary英語版での「Coordinated Universal Time」の意味, ウィキペディア英語版での「Coordinated Universal Time」の意味, 「Coordinated Universal Time」を解説文に含む英和和英の用語の一覧, 英和辞書の「Coordinated Universal Time」の用語索引, Creative Commons Attribution-ShareAlike (CC-BY-SA). As a result, the SI second is close to 1/86400 of a mean solar day in the mid‑19th century. A decision whether to remove them altogether has been deferred until 2023.[2]. GPS time always remains exactly 19 seconds behind TAI (neither system is affected by the leap seconds introduced in UTC). By extension, it is not possible to compute the precise duration of a time interval that ends in the future and may encompass an unknown number of leap seconds (for example, the number of TAI seconds between "now" and 2099-12-31 23:59:59). [29][30], In a controversial decision, the frequency of the signals was initially set to match the rate of UT, but then kept at the same frequency by the use of atomic clocks and deliberately allowed to drift away from UT. It is, within about 1 second, mean solar time at 0° longitude. [49], ITU‑R Study Group 7 and Working Party 7A were unable to reach consensus on whether to advance the proposal to the 2012 Radiocommunications Assembly; the chairman of Study Group 7 elected to advance the question to the 2012 Radiocommunications Assembly (20 January 2012),[50] but consideration of the proposal was postponed by the ITU until the World Radio Conference in 2015. Naval Observatory started to develop atomic frequency time scales; by 1959, these time scales were used in generating the WWV time signals, named for the shortwave radio station that broadcasts them. Standard abbreviated as `` UTC '' also adopted leap seconds are timed to it... That lies between UTC−1 and UTC+1, See, this article is about the time standard abbreviated as `` time! But would take effect slowly over several centuries, the SI second redefined... From the central UTC time TAI since 1958 every year related to TAI! 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