I don't understand the downvotes of the poster above correctly highlighting that GPS does not use UTC. GPS does not use UTC, it uses GPS time [1], which is at

I don't understand the downvotes of the poster above correctly highlighting that GPS does not use UTC. GPS does not use UTC, it uses GPS time [1], which is at a constant offset to International Atomic Time, TAI [2], which was in sync back in 1958 with Universal Time [3], on which UTC is based. GPS, TAI, and UTC use SI seconds, while UT1 doesn't (a UT1 second is 1/86400 of a complete rotation of earth). Of course they are all related, but, hey, all time scales are somewhat related and "track each other", given some (time-dependent) offset. Fact is that GPS doesn't run on UTC. [1] https://en.wikipedia.org/wiki/Global_Positioning_System#Leap_seconds https://en.wikipedia.org/wiki/Global_Positioning_System#Leap... [2] https://en.wikipedia.org/wiki/International_Atomic_Time https://en.wikipedia.org/wiki/International_Atomic_Time [3] https://en.wikipedia.org/wiki/Universal_Time https://en.wikipedia.org/wiki/Universal_Time