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Hi! Is your time servers synchronized to GMT (mean solar time at the Royal Observatory in Greenwich) or UTC (Coordinated Universal Time)?

The RFC requires GMT, but most time servers synchronizes to UTC. It could be a difference of up to 0.9 seconds between GMT and UTC.



> It could be a difference of up to 0.9 seconds between GMT and UTC.

Not in this context. In the context of ASN.1, NTP, POSIX, etc, GMT is a timezone equivalent to UTC+00:00. UT1 and DUT1 don't figure into it.


GMT was abolished at the end of 1971, when the Greenwich observatory started distributing UTC as its official timescale. At that time the observatory was based in Herstmonceux, so GMT was calculated from a model rather than being based on observations made from the transit instruments in Greenwich.




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