[GPS]
A continuous time scale, without leap seconds, defined by the GPS control segment and maintained by atomic clocks onboard monitor stations and satellites. It started (starting epoch) at 0h UTC (coordinated universal time, midnight) 5th-6th January, 1980 (6.d0). GPS time is synchronized with the UTC(USNO) at a 1 microsecond level, and kept within 25 ns.