[LEAPSECS] inaugural effects of abandoning leaps

[Steve Allen]

The news yesterday made a point of the time for the inauguration of
Obama's 2nd term...

    Twentieth Amendment to the US Constitution

    Section 1.  The terms of the President and Vice President shall
    end at noon on the 20th day of January, and the terms of Senators
    and Representatives at noon on the 3d day of January, of the years
    in which such terms would have ended if this article had not been
    ratified; and the terms of their successors shall then begin.

    Section 2.  The Congress shall assemble at least once in every
    year, and such meeting shall begin at noon on the 3d day of
    January, unless they shall by law appoint a different day.

This was proposed in 1932 and ratified in 1933.  At that time 15 USC
Sec 261 (the Calder Act of 1918) specified that standard time was
based on the "mean astronomical time" of meridians spaced at 15-degree
intervals west of Greenwich.  This was amended in 1966 to be "mean
solar time", and in 2007 to be Coordinated Universal Time.

For this action performed by humans it would be difficult to imagine
consequences for a race condition where the oath was administered a
few seconds off from whatever is the legal meaning of noon.  This is
because either side of noon is reckoned as the same day.

The issues would be different around midnight.  This is a condition
where a race has been seen.  Before the Y2K agreement in the FITS data
format for astronomy the DATE keywords did not allow the inclusion of
a time, so time was stored in a separate keyword.  Careless use of the
system calls regarding time could lead to the DATE keyword being on
one side of midnight and the time keyword on the other, thus producing
a full day ambiguity about the data in the file.

Avoiding that ambiguity is, of course, the same reasoning by which the
effective dates of insurance policies and time of first showing of new
releases of blockbuster movies is 12:01 AM.

In January 2012 the ITU-R RA avoided voting on the new leap-free draft
of TF.460.  Just after that the WRC produced Resolution COM6/20 which
then became WRC-15 agenda item 1.14.  It points out that the current
Radio Regulation 2.5 implies that UTC is connected with earth
rotation:

    2.5 Whenever a date is used in connection with Coordinated
    Universal Time (UTC), this date shall be that of the prime
    meridian at the appropriate time, the prime meridian corresponding
    to zero degrees geographical longitude.

So without even considering the effects on insurance policies and
movie theaters, the ITU-R has recognized that abandoning leap seconds
has the effect of making their own regulations self-inconsistent.

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