[fitsbits] Leap Second questionnaire

[Mark Calabretta]

On 2000/07/05 Demetrios Matsakis issued a report to the respondees of the
previous leap second questionnaire in which he stated:

   A discussion of the motivations for a
   change and of possible solutions has been published by McCarthy and
   Klepczynski in the Innovations Section of the November, 1999 issue of
   GPS World.  The authors consider the most significant reason for a
   change to be keeping spread-spectrum communication systems and
   satellite navigation systems compatible with each other and with civil
   times.  Another reason is the emerging need in the financial community
   to keep all computer time-stamps synchronized.

Matsakis states that one half of the respondents of the previous
questionnaire were opposed to a change while one quarter were in favour
(and the rest indifferent).  In summarizing the arguments for either side
he states that for those in favour:

   Forty-eight responses in favor were received, several from people who
   experienced minor problems now in handling leap seconds, such as
   confusion due to GPS time being currently 13 seconds offset from UTC
   and computer errors at the time of the leap seconds. Along with
   responses based upon reasons already covered in the GPS World Article,
   there were also three from the highly undersampled group of computer
   programmers, which pointed out the growing need to synchronize diverse
   computers to one second accuracy and the difficulties of doing so in an
   when dates of future leap seconds were unpredictable.

Thus, it is apparent that the "GPS World" article is critical to
understanding the arguments in favour of eliminating leap seconds
(perhaps a surprising place to canvas such a major change to civil
timekeeping).

Question: does anyone on this list know of any other source of
justification for dropping leap seconds?

"GPS World" has a web site at http://www.gpsworld.com, but it does not
include the back-issue containing the article.  The article itself was
sent to the leapsecs list on 2000/07/10 by Demetrios Matsakis.  I have
attached it here on the assumption that, like me, most others on this
list will not have seen it before.

As I see it, the main arguments are

   a) Leap seconds are a nuisance, moreso now for some than others, but

   b) They will become a much greater nuisance for all in the future
      (on a timescale of centuries) because of the *quadratic*
      deviation of UT1 from TAI.

Note that while Fig. 1 of the article demonstrates (b) via a somewhat
unconvincing least squares fit to the observations, mathematically a
quadratic dependence must arise as a consequence of the approximately
uniform deceleration of the Earth's rotation rate due to Earth-Moon
tidal coupling.

However, my assessment is that the current system will last for at least
200 years (one leap second every three months) and as it is by no means
certain that humans won't have become extinct by that time the problem
is best left for future generations.

Mark Calabretta
ATNF

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