[LEAPSECS] historic clock offsets

Steve Allen sla at ucolick.org
Wed Nov 5 09:44:09 EST 2014

On Wed 2014-11-05T11:11:38 +0000, Tony Finch hath writ:
> Does anyone know where SOFA iauDat got its data for 1960 from? Because
> that predates the USNO table.

I suspect they are the data from US NBS which Seidelmann included in
the Explanatory Supplement.  The numbers from BIH Bulletin Horaire
during that year are consistent with some other references which say
that UK NPL and US NBS did not get MSF and WWV aligned onto the new
"coordinated" system until after the start of the year.  My casual
impression from Bulletin Horaire is that they got the transmissions
lined up about a week into the year, and during that first year both
sites just let their chronometers go with no attempt to resync.

There are measurements of how far off were all the time scales
starting from the inception of the BIH.  I have a sampling of the
numbers from 1960 in images here

The first few are a report on the initial effort to create an
integrated atomic time scale.  Note that those pages were published as
much as a year after the dates of their data.

The last few are from the year end summary for 1960.  There are plots
of how far each observatory deviated from Heure Definitive (which at
that point had been and would continue to be UT2).  There are offsets
of each observatory during those months.  There are measures of the
offsets of each radio broadcast service during those months.

The plots of deviations are kindof scary big, and I take them as
powerful rationale that the IANA tz timezone project should make
no effort to calculate sub-second offsets for far flung peoples.

Steve Allen                 <sla at ucolick.org>                WGS-84 (GPS)
UCO/Lick Observatory--ISB   Natural Sciences II, Room 165    Lat  +36.99855
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