Re: [Ntp] Leap second draft

[Steve Allen <[e-mail]>]

Daniel Franke notes that I did not send this and the
next message to the list.

Greetings Daniel Franke,
On Fri 2019-03-29T20:57:42+0100 Daniel Franke hath writ:

> Network Working Group                                          D. Franke
> Internet-Draft                                                    Akamai
> Updates: 5905 (if approved)                               March 29, 2019
> Intended status: Standards Track
> Expires: September 30, 2019

>    At their inception in 1972, UTC and TAI were equal.  Since then,

No, please look at the second plot on
https://www.ucolick.org/~sla/leapsecs/amsci.html
and at the third plot on
https://www.ucolick.org/~sla/leapsecs/deltat.html

As of 1972 TAI - UTC was reset to exactly 10 SI seconds
Since then there have been 27 leap seconds.

>    Both TAI and UTC are canonically represented by a count of days,
>    hours, minutes, and seconds (including fractional seconds) since
>    their epoch at solar midnight at the prime meridian on January 1,
>    1958.

The epoch of the TAI that we now have is 1961-01-01T20:00:00 UT2
see the reason why at
https://www.ucolick.org/~sla/leapsecs/taiepoch.html

There was also a step in that time scale on 1962-01-01
because of the change of the canonical formula for UT2 and
the change from FK3 catalog to FK4 catalog.
https://www.ucolick.org/~sla/leapsecs/seasonal.html

These events are documented in issues of Bulletin Horaire.

Also note that the rate of TAI was modified by a step
on 1977-01-01, and other rate changes have been applied.

>           While neither TAI nor UTC is formally defined for any date
>    earlier than the epoch, this nit is routinely ignored by allowing the
>    day number to be negative and by assuming the fiction that prior to
>    1958 Earth's rotation was always perfectly regular with respect to
>    proper time.

Which epoch?  POSIX epoch?
Any date at which there is general agreement among all parties
about when it happened is an epoch.  Please be specific and
never use merely "the epoch".

TAI was not defined until 1971-10-04 when the CGPM authorized it.
Before then there were only various atomic time scales of
various agencies.  It was the atomic time scale of the BIH that
became TAI.

UTC was not named by any official document until 1974-07 when the 13th
Plenary Assembly of the CCIR approved Recommendation 460-1.

--
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