Coordinated Universal Time


January 21, 2022

Coordinated Universal Time (UTC, English: Coordinated Universal Time, German: Koordinierte Weltzeit, French: Temps Universel Coordonné) is the time of the atomic time system derived from International Atomic Time (TAI), the UT1 world. Refers to a reference time adjusted to tune in at times.


Coordinated Universal Time is a time system maintained by the International Bureau of Weights and Measures (BIPM) with the support of the International Earth Rotation and Reference System (IERS), which is the basis for standard frequency and time signal emission, and the International System of Units (SI). It has the same rate as International Atomic Time based on seconds, but differs by an integer second. Leap second adjustment is performed to insert or remove seconds in order to closely match UT1 universal time. The difference between UT1 and UTC can be found on the website of the International Earth Rotation and Reference Systems Project. Standard time around the world is based on Coordinated Universal Time. Japan Standard Time (JST) is 9 hours ahead of Coordinated Universal Time.



The abbreviation for Coordinated Universal Time is UTC. Coordinated Universal Time is an acronym for "CUT" for coordinated universal time, "TUC" for temps universel coordonné for French, and "TCU" for tempo coordinato universale for Italian. , The International Telecommunication Union (ITU) has a single abbreviation, which means “UTC” or Universal Time (UT) and is consistent with existing UT0, UT1, etc. There are some informal notations such as English: “Universal Time, Coordinated”, French: «universel temps coordonné», which are back-formed from the abbreviations.


Coordinated Universal Time has several terms that are treated as synonyms in certain areas for historical reasons. GMT and Z are recognized as synonyms for UTC in the fields of navigation and communications. If the meridian is expressed as a positive number and the west longitude as a negative number, corresponding to one letter of the alphabet with a time difference of every hour, 15 A, 30 B, 45 C, 60 D, 75 E, 90 F. , 105 G, 120 H, 135 I, 150 K, 165 L, 180 M, -15 N, -30 O, -45 P, -60 Q, -75 R, -90 S, -105 T, -120 U, -135 V, -150 W, -165 X, -180 Y, 0 Z. The time zone centered on the prime meridian is represented by Z, and the word used for the letter Z in the spelling alphabet in communications is Zulu, so "UTC" is sometimes referred to as "Z o'clock" or "Zulu time". .. When dealing with the maximum time precision in integer seconds, GMT and Universal Time (UT) are used to mean UTC, and GMT is replaced with UTC or UT.

Relationship with International Atomic Time

International Atomic Time is a time system defined by the International Committee for Weights and Measures (CIPM) in 1970. Defined as "the reference time coordinates set by the International Time Bureau (BIH) based on the readings of atomic clocks operated by several institutions, according to the definition of seconds, which is the unit of time in the International System of Units." ing. Since 1988, the International Bureau of Weights and Measures has managed to maintain an integer second difference at a rate in which Coordinated Universal Time after 1972 is perfectly synchronized with International Atomic Time, instead of the International Time Bureau. The starting point for International Atomic Time is UT2, Universal Time, January 1, 1958, 0:00:00. The realization of each country is carried out by the National Research Institute for Time, etc., and the atomic clock data is transmitted to the International Bureau of Weights and Measures to participate in the calculation of the international time scale.

Universal Time and Adjustment

UT1 Universal time is set by the International Atomic Time and Standards Project based on the earth rotation observation data of each country's astronomical observatory, and the rotation cycle of the earth fluctuates depending on the length of the cycle of about 10 years and irregularity in millisecond units. Since 1972, the agreement universal time has introduced a leap second adjustment that inserts or removes seconds to ensure an approximate match with UT1 universal time while maintaining an integer second difference from international atomic time, with a deviation of within 0.9 seconds. To fit,

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