Re:Why UTC is used as the acronym for Coordinated Universal ...
by klodolph on Tuesday October 22, 2019 @10:13AM
(#21323791)
> Technically UTC is not the same as GMT. The two can differ by up to 0.9 seconds.
It’s UT1 and UTC that differ by up to 0.9 seconds. GMT and UTC are equal unless you’re in a specialized field (navigation) where it is considered to be UT1. Otherwise, GMT is just the name of a time zone UTC+0000.
TAI measures seconds. UT1 measures the earth’s rotation. UTC combines these by using TAI plus a changing offset to keep within 0.9s of UT1.
It’s UT1 and UTC that differ by up to 0.9 seconds. GMT and UTC are equal unless you’re in a specialized field (navigation) where it is considered to be UT1. Otherwise, GMT is just the name of a time zone UTC+0000.
TAI measures seconds. UT1 measures the earth’s rotation. UTC combines these by using TAI plus a changing offset to keep within 0.9s of UT1.