Ian Batten via LEAPSECS <leapsecs@leapsecond.com> wrote: > > An obvious example is the UK. Our legal time is GMT with DST, usually taken > to be > UT1 with DST. Our "de facto" civil time is UTC with DST, and over the years > this > has become more and more ingrained (the "Greenwich" pips on the hour on Radio > 4 > are now UTC, the MSF transmitter is UTC with a 0.1s resolution DUT1 embedded > in > the data stream, etc, etc). Everyone calls it GMT, and government discussions > about leapseconds are often in terms of GMT (yes, obviously a nonsense), and > the > law definitely calls it GMT, but here we are: custom and practice makes it > UTC.
My understanding from reading a history of the Greenwich Observatory at Herstmonceux is that the UK Government's official time signals (from the RGO and NPL) were UTC since the 1960s, and switched to leap seconds in 1972. Before UTC, GMT was UT2. (I don't know when GMT was last equivalent to UT1.) GMT's specification has changed several times, so it is not "obviously" a nonsense to make it equivalent to UTC. It is still a mean time, though it prioritizes frequency stability at the cost of larger phase differences. Tony. -- f.anthony.n.finch <d...@dotat.at> http://dotat.at/ Hebrides: Southwesterly 5 to 7, perhaps gale 8 in northwest later. Rough in south, very rough in north. Occasional rain. Moderate or good. _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
