[LEAPSECS] complete history of UT2

[Michael Deckers]

 ???? On 2019-06-05 05:28, Steve Allen wrote:
> 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.


 ???? Thanks! That clarifies that the 5 ms step down in UTC at 1961-01-01
 ???? has nothing to do with the change in the formula for UT2 as a
 ???? function of UT1.

 ???? Nowadays, the role of UT2 is reduced: it is given in Bulletin A
 ???? as a linear function of UTC, as a means to extend the prediction
 ???? of UT1 as given in the Bulletins.

 ???? Michael Deckers.