Re: [LEAPSECS] GMT -> UTC in Australia

From: Steve Allen <>
Date: Wed, 23 Feb 2005 19:10:58 -0800

On Wed 2005-02-23T09:07:30 -0700, Rob Seaman hath writ:
> A big question throughout all of the UTC discussions over the past five
> years is who "they" are and whether they have the ability to form a
> clear and consistent intent in the first place.

I think that the cast of characters is pretty clear from reading
the materials referenced in my bibliography web page. It is very
clear that there is a contingent strongly pushing for a "uniform"
time scale.

> Determining prior
> worldwide legal intent - and forming any (hopefully improved) future
> international legal consensus on civil time - should both be key to any
> proposed change to UTC.

Intent is one thing, and practicality is another.

>From the evidence referenced in the bibliography I think it is safe to
presume that ITU-R sector members have been tasked to induce their
local legislators to change the wording of laws from GMT to UTC.

I note, however, that as a result of publishing the bibliography these
efforts, and the individuals effecting them, have become more
difficult to follow. I don't have an international network of spies,
and it looks like that's what is now needed if someone really wants to
find out who is doing what, and why.

So, yes, I am in mildly paranoid agreement with Rob in that there are
indications which resemble a secret society trying to subvert the
order of the world. On the other hand, by keeping the definition and
justification for UTC in a set of proprietary and inaccessible
documents, it could be said that UTC has always been in the hands of a
secret society.

Indeed, that was really true before UTC. In the 1950s when time was
still under the control of the astronomers, the decisions were made
privately. There is no historical record available which documents
the creation of UT0, UT1, and UT2 by those names. All we know is that
Markowitz (then president of IAU Comm 31) managed to get the BIH and
the various national time bureaus to begin to use them.

The general public and legislatures of the world have never had the
opportunity to debate the goals behind civil time. Nobody asks for
their views on intent.

Practically speaking, GMT ceased to exist as a result of three
events spread over three decades.

UTC as defined by the BIH with rubber seconds (or elastic seconds)
became the de facto standard for national time agencies, and thus the
prime meridian for time shifted from the Greenwich transit to the
International Meridian defined by the long history of the BIH's
averages of all broadcast time signals. To the world at large the
effect of changing the length of the second annually and inserting
occasional steps of 50 to 100 ms were just as inconsequential as the
resetting of the national master clocks had always been. To the
technicians in charge of time distribution those changes were
extremely impractical.

The CCIR changed UTC to atomic seconds with leaps. Again, to the
world at large, the effect of resetting all clocks by a second was
inconsequential. To the technicians the leaps were more tolerable
than the previous system.

The IAU replaced Newcomb's expressions for UT (and thus UT1) with new
expressions which ignored the existence of observations of the sun and
which implicitly demanded a globally self-consistent coordinate
system. (Ironically such a system had been suggested by the French
delegates to the IMC a century earlier, and in the IMC protocols it is
evident from his statements that Newcomb had recognized the sense of
such a system before he was ushered out by the majority delegates, who
were probably mollified by the implications of their own American
expert agreeing with the French, because they wanted to assert
Greenwich as prime.)

The BIH ceased to exist, being replaced by the IERS.
By this date there were effectively no more observations of earth
rotation using transit instruments, so all direct connection of time
with Greenwich had come to an end.

> One has to wonder whether any individuals
> involved in the legal UTC debate in Australia were aware of the leap
> second controversy in the precision timing community.

Yes. But I can't say whether they value the immediate practicality of
uniform time over the need to change all time zones by an hour 600
years from now, and more and more often after that.

> Whether this was
> the case or not, the wording of the quoted article makes it clear that
> UTC is being sold to everyday Australians in its original sense of
> being a continuing approximation to GMT:

Which is consistent with the text of approvals granted to the UTC by
the IAU at the General Assembly in 1973 and by the CGPM in 1975
Both recognized that UTC with leap seconds provides mean solar time.

The draft ITU-R documents which have leaked out indicate disregard for
the advice of the Torino conference which specified that a uniform
time scale should have a name other than UTC.

If the wording of the Australian legislation does not explicitly
indicate that UTC is being adopted with the intent that it should
continue to conform to mean solar time, then the uniform time
contingent of the ITU-R wins.

Given that IAU does not currently have an expression which can be used
for the definition of mean solar time, there is little practical
alternative for a legislature. If they make a change now, they can
only adopt UTC. The alternative would be to wait and see if the IAU
bothers to define a new quantity for mean solar time.

I suppose that such a new IAU-approved mean solar time might be called
Analemmatic Universal Time, or UTA, with the intent that it should
define a new version of Newcomb's fictitious mean sun. It would be
based on the long term integrations of the orbital motion which are
employed in the new precession and nutation models which underlie the
new UT1 expressions.

Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064      Voice: +1 831 459 3046
PGP: 1024/E46978C5   F6 78 D1 10 62 94 8F 2E    49 89 0E FE 26 B4 14 93
Received on Wed Feb 23 2005 - 19:11:35 PST

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