[LEAPSECS] complete history of UT2

[Steve Allen]

I have plowed through enough of Bulletin Horaire to find the complete
history of UT2.
https://www.ucolick.org/~sla/leapsecs/seasonal.html
Missing from the earlier version of the plots on this web page was the
story of how exactly the BIH performed the transition between the
first version of UT2-UT1 and the second version.
Naively the change of the expression requires a jump of 6 ms
at the beginning of 1962, but that is not what the BIH dictated.

Look at the middle plot and see how the year started along one
curve and finished along the other.

This also means that it is possible to make a complete regression of
the values of TA-UT1 back to the inception of Essen's original cesium
chronometer in 1955 July.  Doing that requires modifying each of the
varying forms of the tabulations in the pages of Bulletin Horaire so
that everything is transformed into a single reference system.

--
Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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