Greenwich Mean Time
, Greenwich Time mean solar time on the 0? meridian passing through Greenwich, England, measured from midnight: formerly a standard time in Britain and a basis for calculating times throughout most of the world, it has been replaced by an atomic timescale
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
Greenwich mean time
(GMT) The mean solar time on the longitude (0°) at Greenwich, in the UK, reckoned from midnight. In 1928, on the recommendation of the IAU, GMT became known as universal time (UT) for scientific purposes; the version coordinated universal time, available since 1972 from broadcast signals, is now generally known as GMT.Collins Dictionary of Astronomy © Market House Books Ltd, 2006
Greenwich mean time
[′gren·ich ′mēn ¦tīm] (astronomy)
Mean solar time at the meridian of Greenwich. Abbreviated GMT. Also known as Greenwich civil time; universal time; Z time; zulu time.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
Greenwich Mean Time (GMT)
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
Greenwich Mean Time
(time, standard)(GMT) The local time on the Greenwich
meridian, based on the hypothetical mean sun (which averages
out the effects of the Earth's elliptical orbit and its tilted
axis). GMT is the basis of the civil time for the UK.
In 1925 the reference point was changed from noon to midnight and it was recommended that the term "Universal Time" should be used for the new GMT.
Authorities disagreed on whether GMT equates with UT0 or UT1, however the differences between the two are of the order of thousandths of a second. GMT is no longer used for scientific purposes.
In 1925 the reference point was changed from noon to midnight and it was recommended that the term "Universal Time" should be used for the new GMT.
Authorities disagreed on whether GMT equates with UT0 or UT1, however the differences between the two are of the order of thousandths of a second. GMT is no longer used for scientific purposes.
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UTC
(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 © 1981-2025 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.