Brian Inglis <Brian.Inglis@SystematicSw.ab.ca> wrote:
On 2016-11-09 03:23, Tony Finch wrote:
Brian Inglis <Brian.Inglis@SystematicSw.ab.ca> wrote:
I think UK legal time is also still some variety of GMT, as may be some other Commonwealth countries.
British law refers to mean time, but the Greenwich Observatory and subsequently NPL have only provided UTC since it started.
Royal Observatory Greenwich and Royal Greenwich Observatory (at Herstmonceaux 1947-1990, then Cambridge 1990-1998, before closing) provided astronomical and navigational products for GMT, GCT, GMAT, GMST, UT, UT0, UT1, UT2 (used for radio time signals), ET, etc.
UT2 might have been used for radio time signals in the 1960s (though I thought it was rubber-seconds UTC then) but after 1972 British general-purpose time signals were all UTC. See for example section 5.5.6.1 in http://www.lib.cam.ac.uk/deptserv/manuscripts/RGO_history/rgo_home_ch5.html
They did participate in CUT, originally from RGO, NPL, USNO, then BIH. The atomic standard TAI, its civil UTC derivative, and frequencies, are physical standards set and provided by NMIs coordinated by the BIPM.
Tony. -- f.anthony.n.finch <dot@dotat.at> http://dotat.at/ - I xn--zr8h punycode Sole, Lundy, Fastnet: Northwest 5 or 6, backing south 3 or 4, increasing 5 or 6 later in Sole and Fastnet. Rough or very rough. Showers. Moderate or good.