An Etymological Dictionary of Astronomy and Astrophysics
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An international high-precision time standard based on the Greenwich Mean Time and adjusted to compensate for divergence from atomic time. It is based on the non-uniform rotation of the Earth (UT1) and the perfectly uniform international atomic time (TAI). UTC differs from TAI by the total number of → leap seconds, so that UT1-UTC stays smaller than 0.9 sec in absolute value.

→ coordinate; → universal; → time.

A measure of time that conforms, within a close approximation, to the mean diurnal motion of the Sun and serves as the basis off all civil timekeeping. The local civil time for a position on the Greenwich meridian.

→ universal; → time.

Sale as → Coordinated Universal Time (UTC).

→ Coordinated Universal Time (UTC).