June 25, 2014
11:54 a.m.
Paul Eggert <eggert@cs.ucla.edu> wrote:
Technically, GMT can refer to either a civil day (day starts at midnight) or an astronomical day (day starts at noon), and UT avoids this twelve-hour ambiguity by standardizing on the civil day. Until 1952 the US Naval Observatory attempted to resolve the ambiguity by using the term "Greenwich Civil Time" (GCT) for civil-day GMT but that terminology did not catch on widely (it wasn't used in Britain), whereas UT has.
Britain (the RGO) switched from the astronomical to the civil meaning of GMT in 1925. http://www.apparent-wind.com/gmt-explained.html Tony. -- f.anthony.n.finch <dot@dotat.at> http://dotat.at/ Irish Sea: Southeast 4 or 5. Slight. Occasional rain. Moderate or good.