On Wed 2015-03-04T07:42:46 +0000, michael.deckers via LEAPSECS hath writ: > On 2015-03-04 02:23, Steve Allen wrote on the
> >Getting meaninglessly pedantic, in Survey Review v19 #143 p7 (1967) > >A.R. Robins had been talking with Sadler and Smith and with that > >information in hand he wrote that atomic time was identical to UT2 at > >1958-01-01 T 20:00:00 Z > Well, there is not only personal recollections: > > RECOMMENDATION S 4 (1970) of the 5th Session of the > Consultative Committee for the Definition of the Second: > 4. The origin of International Atomic Time is > defined in conformance with the recommendations > of the International Astronomical Union (13th > General Assembly, Prague, 1967) that is, this scale > was in approximate agreement with 0 hours UT2 > January 1, 1958. A resolution does not change what had been done by the folks running the broadcasts over a decade earlier, nor does it repair the deficiencies in what they had done over that entire interval. A.R. Robins talked with H.M. Smith. Smith had been there making the UK time broadcasts happen. If Smith said that the UK versions of the atomic time scale and the UT2 time scale were aligned at 1958-01-01T20 then that is likely the way the calculations to do that alignment were performed, and likely based on the hour of the day that the ionospheric conditions were most conducive to allowing the best comparison with other transmitters. It is instructive to read BIH Bulletin Horaire for the actual history;, to see the ways that the radio broadcasters attempted, succeeded, and failed at their mandate of maintaining continuously operating transmitters based on continuously operating chronometers; to see the issues with Anna Stoyko's initial, painstaking efforts to reconstruct the history of received radio time signals into the first atomic time scale; to see the number of times that the broadcasters changed their strategies and the number of times that the BIH changed their algorithms and recomputed what past issues should have said the time was. -- Steve Allen <[email protected]> WGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ LEAPSECS mailing list [email protected] https://pairlist6.pair.net/mailman/listinfo/leapsecs
