[LEAPSECS] happy birthday UTC, sortof

[Steve Allen]

Attached is an image of
Bulletin Horaire series J number 1 page 2
This issue is for the dates 1964 January/February.  It is the first
issue produced by Bernard Guinot as the Stoykos were retiring after
many decades of service.  It is the earliest publication containing
the term UTC or TUC that any of us on LEAPSECS has been able to find.

Rule number 1, the frequency offset, dates from the original US/UK
agreement to coordinate their broadcast time signals in 1959.  That
the BIH should dictate these values had been approved by URSI in 1961
and the IAU in 1961, but the restriction of frequency steps of 50e-10
was not in CCIR Rec 374 (1963).

Rule number 2 is the same as in CCIR Rec 374 (1963).  The original
time step size had been 50 ms in 1961, but it was relaxed to 100 ms.

Note, however, that the page refers to a CIPM declaration in 1964
October and a CCIR allowance in 1965.  On subsequent pages of this
issue are events as late as 1965 May 1, and the issue was received
at Lick late in 1965 June.  So at this point the Bulletin Horaire
was coming out more than a year after its dated bimonthly period.
(And in 1965 the USNO, one of the sources of the BIH inputs, was
referring to their broadcasts as UT2C.)

The later pages discuss the values of TAi, temps atomiques individueles,
for the 3 contributors to A3 and all the other contributors to AM.  The
values of TAi differed by as much as 0.02 s in early 1964.

They also give the values of the little jumps in the time signals of
the various emitters of coordinated time signals.  That is not the 100
ms jumps prescribed by BIH, just little ones of as much as 5 ms which
various transmitters of coordinated time, including LORAN, performed
at various points.

Based on the cover date of the Bulletin Horaire I was thinking that
2014 is the 50th birthday for "UTC", but reading closer into the details
makes it really hard to say when the birthday of UTC was.

--
Steve Allen                 <sla at ucolick.org>                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
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