Current official world time reference for civil and scientific purposes. Coordinated Universal Time is measured from six standard atomic clocks at the International Bureau of Weights and Measures (BIP [..]

By international agreement, the local time at the prime meridian, which passes through Greenwich, England. Prior to 1972, this time was called Greenwich Mean Time (GMT) but is now referred to as Coord [..]

time standard based on atomic time that is coordinated with rotational timethe cycles of day and nightby the introduction of leap seconds at certain intervals. For practical purposes, sometimes referr [..]

Replaced Greenwich Mean Time (GMT) as the world standard for time in 1986. UTC uses atomic clock measurements to add or omit leap seconds each year to compensate for changes in the rotation of the ear [..]

Time scale based on the second (SI), as defined and recommended by the CCIR, and maintained by the Bureau International des Poids et Mesures (BIPM). For most practical purposes associated with the Radio Regulations, UTC is equivalent to mean solar time at the prime meridian (0° longitude), formerly expressed in GMT. [NTIA] [RR] Note 1: The maintena [..]

Please see UTC (Coordinated Universal Time).

The international time standard based on time kept by atomic clocks.

This time system uses the second-defined true angular rotation of the Earth measured as if the Earth rotated about its Conventional Terrestrial Pole. However, UTC is adjusted only in increments of one [..]

A time standard that is not affected by time zones or seasons. Time measured in coordinated universal time labeled with the term Zulu. It is used so that people around the world can communicate about [..]

The time in the zero degree meridian time zone. In order to convert to Eastern Standard Time, subtract 5 hours (Eastern Daylight Time subtract 4 hours). For example, 0900 UTC is 4:00 AM EST or 5:00 AM EDT.

see UTC

By international agreement, the local time at the prime meridian, which passes through Greenwich, England. Prior to 1972, this time was called Greenwich Mean Time (GMT) but is now referred to as Coordinated Universal Time or Universal Time Coordinated (UTC). It is a coordinated time scale, maintained by the Bureau International des Poids et Mesures [..]

By international agreement, the local time at the prime meridian, which passes through Greenwich, England. It was formerly known as Greenwich Mean Time, or sometimes simply Universal Time. There are 24 time zones around the world, labeled alphabetically. The time zone centered at Greenwich has the double designation of A and Z. Especially in the mi [..]

The new term for Greenwich Mean Time. Computer models and aviation forecasts are two examples in meteorology where its better to use a standard time than convert back to local time. In winter, South-east Australia is 10 hours ahead of UTC time, and New Zealand is 12 hours ahead. This increases by one hour during the daylight savings period over sum [..]

By international agreement, the local time at the prime meridian, which passes through Greenwich, England. Therefore, it is also known as Greenwich Mean Time (GMT), or sometimes simply Universal Time [..]

– see Universal Time

A high-precision atomic time standard (''abbreviation'' '''UTC''')