Gps (System) Time - Leica GR10 Operational Manual

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GPS (System) Time

The time scale to which GPS signals are referenced. GPS Time derives from a composite or "paper" clock consisting of all
operational monitor station and satellite atomic clocks. It is steered over the long run to keep it within about 1 micro-second of
UTC, as maintained by the Master Clock at the U.S. Naval Observatory, ignoring the UTC leap seconds. At the integer second
level, GPS Time equalled UTC in 1980, but currently, due to the leap seconds that have been inserted into UTC, it is ahead of
UTC by 10 seconds.
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