[LEAPSECS] epoch of TAI, and TAI vis a vis GPS

[michael.deckers]

   On 2015-03-04 02:23, Steve Allen wrote on the
   epoch of TAI:

> 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
>
> This, of course, disagrees with Guinot's memoir, but the various
> realizations of UT2 then differed by centiseconds and the different
> versions of atomic time were subsequently realigned by milliseconds.
> And that date of 1958-01-01 was decided ex post facto at the 1959
> August meetings where the US and UK decided to try coordinating their
> broadcast time signals using cesium.  So there really isn't an epoch
> for TAI.

   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.

   Michael Deckers.