Hello! I'm new to the list and I have a question about time systems. The context is that someone is going to be communicating timestamps to me in TAI formatted as the number of elapsed seconds since 1958 Jan 1 00:00:00. To make sure that I understand how this is being calculated, I reviewed the history of the establishment of TAI and UTC in the late 60s and early 70s. I understand why 1972 Jan 1 00:00:00 UTC == 1972 Jan 1 00:00:10 TAI and why TAI is now 37 seconds ahead of UTC. I can also see that propagating backwards from the 1961 time conversion formulas to 1958 Jan 1 gives TAI - UTC very close to 0 (within about 2 milliseconds). So, it makes sense to use 1958 Jan 1 00:00:00 UTC == 1958 Jan 1 00:00:00 TAI as the 0 epoch for TAI in seconds.
But, I also came across this statement: *Loran-C*, Long Range Navigation time, is an atomic time scale implemented by the atomic clocks in Loran-C chain transmitter sites. Loran time was zero at 0h 1-Jan-1958 and since it is not perturbed by leap seconds it is now ahead of UTC by 27 seconds. Loran-C time seems to be currently ticking synchronously with TAI but is 10 seconds behind TAI. Does that mean that when TAI and UTC were defined/synchronized in 1972, that the extra 10 seconds were not added to Loran time? And that the statement above should be that 1958 Jan 1 00:00:00 UTC == 1957 Dec 31 23:59:50 Loran? Thanks, Scott -- "Of what avail are forty freedoms without a blank spot on the map? " — Aldo Leopold _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.