Coordinated Universal Time

Also found in: Dictionary, Thesaurus, Acronyms, Wikipedia.

coordinated universal time

(UTC) See universal time.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Coordinated Universal Time (UTC)

A time based on the fundamental properties of an atom, the isotope of cesium 133, and not on the movement of heavenly bodies. Atomic time increases at a constant rate, unlike the GMT (Greenwich mean time). This time is corrected for the seasonal variation in the earth's rotation about the sun to bring it within +/−0.1 s of GMT. When the correction reaches +/−0.7 s, a positive or negative leap second is applied to the UTC.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

Coordinated Universal Time

(time, standard)
(UTC, World Time) The standard time common to every place in the world. UTC is derived from International Atomic Time (TAI) by the addition of a whole number of "leap seconds" to synchronise it with Universal Time 1 (UT1), thus allowing for the eccentricity of the Earth's orbit, the rotational axis tilt (23.5 degrees), but still showing the Earth's irregular rotation, on which UT1 is based.

Coordinated Universal Time is expressed using a 24-hour clock and uses the Gregorian calendar. It is used in aeroplane and ship navigation, where it also sometimes known by the military name, "Zulu time". "Zulu" in the phonetic alphabet stands for "Z" which stands for longitude zero.

UTC was defined by the International Radio Consultative Committee (CCIR), a predecessor of the ITU-T. CCIR Recommendation 460-4, or ITU-T Recommendation X.680 (7/94), contains the full definition.

The language-independent international abbreviation, UTC, is neither English nor French. It means both "Coordinated Universal Time" and "Temps Universel Coordonn?".


The Royal Observatory Greenwich.

History of UTC and GMT.

U.S. National Institute of Standards & Technology.

UK National Physical Laboratory.

US Naval Observatory.

International Telecommunications Union.

Earth's irregular rotation.
This article is provided by FOLDOC - Free Online Dictionary of Computing (


(Coordinated Universal Time, Temps Universel Coordonné) The international time standard (formerly Greenwich Mean Time, or GMT). Zero hours UTC is midnight in Greenwich, England, which is located at 0 degrees longitude. Everything east of Greenwich (up to 180 degrees) is later in time; everything west is earlier. There are 42 time authorities around the world that are constantly synchronizing with each other. In the U.S., the time authorities are located at the U.S. Naval Observatory (USNO) and the National Institute of Standards & Technology (NIST). See NTP.
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
Coordinated Universal Time is apparently 32 seconds behind International Atomic Time because one adds leap seconds and the other doesn't.
In accordance with national security policy and DoD directives, USNAVOBSY is tasked with maintaining the standard for uniformity of precise time and time interval for DoD components; specifically, all DoD users of precise time and frequency must use that derived from USNAVOBSY, which is referred to as Coordinated Universal Time as maintained by USNAVOBSY, or simply UTC (USNO), as defined in DoD Directive 4650.05 Positioning, Navigation and Timing.
What abbreviation is used for Coordinated Universal Time? (UTC)
In order to keep Coordinated Universal Time (UTC), which evolved from Greenwich Mean Time, in sync with Earth's spin, the scientific community agreed that beginning in 1972 a "leap second" could be inserted at the end of a month when needed.
According to officials, "Oman Air WY 203 flight departed Hyderabad at 09:56 (UTC) and it reached Mumbai airport at 11:35 Coordinated Universal Time (UTC)."
This year's vernal equinox occurs on March 20, at exactly 11:02 Coordinated Universal Time (UTC), or 7:02 am Eastern Daylight Time, ushering in spring in the Northern Hemisphere, and autumn for the Southern.
The extra second is needed to keep Coordinated Universal Time (UTC), defined by atomic clocks, in sync with Earth's rotation.
Summary: Jakarta [Indonesia], April 18 (ANI): An earthquake measuring 5.3 on the Richter Scale hit 226 km North West of Saumlaki, Indonesia at 9:25 UTC (Coordinated Universal Time) on Wednesday, according to the US Geological Survey (USGS).
Today all maps use Greenwich as longitude zero, and nearly all the world's clocks give a nod to the local mean time at this spot: Greenwich Mean Time (GMT)--which with slight modifications evolved into today's Coordinated Universal Time (UT or UTC).

Full browser ?