[LEAPSECS] IAU UTC report

[Rob Seaman]

It's good to see new names appearing on the leapsecs list.  Perhaps new folks might introduce themselves and describe the interest of their institutions in the proposed redefinition of UTC?

> On Nov 8, 2014, at 7:15 AM, Athena Madeleina <athenamadeleina at gmail.com> wrote:
> 
> This is very strange.

The archives of the current list are at:

	https://pairlist6.pair.net/mailman/listinfo/leapsecs

And the archives of the original LEAPSECS list are available from:

	http://www.ucolick.org/~sla/navyls/

Strange or not, my position has remained the same throughout.  Regarding the IAU UTC working group, it was formed:

"Responding to the proposal of recommendation to establish a continuous reference timescale under the International Telecommunication Union, this Working Group will discuss the redefinition of UTC from the perspectives of IAU"  (http://www.iau.org/science/scientific_bodies/working_groups/194/)

The working group report (http://hpiers.obspm.fr/eop-pc/earthor/utc/report_WG_UTC_2014.pdf) was supported by all group members including the chairs, whatever their personal viewpoints.  There has been no other official response of the IAU to the ITU request for comments.

> Also the IAU one indicates little interest outside the WG - not what you would expect if astronomy is about to be thrown to the wolves.

That the topic is esoteric and that it is hard to engage with colleagues is a well-discussed issue on the list.  Lack of interest is not the same as lack of impact.  Astronomers are power users of both Earth rotation time and atomic time.  It is always a big mistake to confuse the two types of timescale, no matter where one's community sits on the cartesian plane of engineering requirements related to both types of axes.  It would be a colossal mistake to build such confusion into the time standards.

> All these persistent distortions convince me that at least the one supporter of a name change I am quoting is really advocating that as a poison-pill.

It is a persistent distortion to call it a name change.  On the other hand a small group has been pushing for a redefinition of UTC for many years.  And many of us have resisted this soft-boiled idea for just as long.  One can avoid both redefinition and so-called renaming by simply defining a new timescale with a new name and having ITU adopt the new timescale.  If the time signals change so will the clocks, whatever our personal positions on the issues.  In that case it would be infinitely preferable for the new timescale to be clearly distinguishable from the old.  Anything else would be the real poison.

For that matter I don't know where the "poison-pill" rhetoric comes from.  As a software systems engineer it makes vastly more sense for Coordinated Universal Time to remain a type of Universal Time, that is, of mean solar time (see Annex 6 of the IAU UTC working group report).  It makes sense to preserve all types of Universal Time for backwards compatibility to avoid risks.  And it makes sense that if a new timescale is created that it be given a new name, not muddy the waters by redefining a timescale that has always had different characteristics.  Defining a new timescale with a new name is a straightforward way to avoid friction in standards-making.

> So the astronomical institutional vote so far is 75% in favor of abolishing leap seconds, with one abstention (IAU).

For a more accurate tally of astronomical and other views on the issue, see:

	http://hpiers.obspm.fr/eop-pc/questionnaire/reponse_questionnaire.html

with 346 responders (out of 466) stating "I am satisfied with the current definition of UTC which includes leap second".  With a much larger sample, that is 74.5% in favor of retaining leap seconds.

> That certainly does not support the idea that abolishing leap seconds is sacrificing astronomy in favor of navigation.

I don't even know what this means.  Both astronomy and navigation - and astronautics and other communities - have requirements depending on Earth rotation.  The IAU did not abstain - for whatever reason it simply did not respond in a timely fashion.  The space agencies that are mischaracterized here as "astronomical institutions" were lobbied behind the scenes - they certainly didn't ask the programmers who are the ones who will have to respond to any change to such a fundamental standard.  

All that said, the current thread isn't about abolishing leap seconds - it's about what a timescale without leap seconds should be called.  If it doesn't function as Universal Time it should not be referred to as a type of Universal Time.

Rob Seaman
National Optical Astronomy Observatory

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