[LEAPSECS] UTC Redefinition Advanced

Rob Seaman seaman at noao.edu
Fri Oct 22 20:03:34 EDT 2010

On Oct 22, 2010, at 3:41 PM, Poul-Henning Kamp wrote:

> Second, therefore I have long time ago said that if the astronomers

> thought this was a real problem, they should send a proposal saying

> "Give us $CALL and we'll shut up and support you" for some Finagle

> adjustment of $CALL big enough to make it worth your while.

By all means, send us your contribution :-) Shouldn't such an issue be part of the proposal being debated?

Why precisely is it that the one sure-fire way to provoke spirited discussion is simply to suggest that the proposal itself sucks as an example of the art of constructing a proposal? Project planning and system engineering are not mystical enterprises. Write a coherent proposal and engage in a coherent (ideally open) process.

> But thirdly, I have a hard time finding more than a single astronomer

> who belives this is a Big Freaking Technological Catastrophe.

Ah yes, another anecdotal argument.

Let's examine the only score card we do have, the "Summary of responses to the Questionnaire on a draft revision of Recommendation ITU-R TF.460.6 (Administrative Circular CACE/516)" (R07-SG07-C-0116!!MSW-E.docx,
http://www.itu.int/md/meetingdoc.asp?lang=en&parent=R07-SG07-C-0116). This one page document tabulates the eight (8) "valid responses" (I don't think they included mine :-) to the questionnaire:

1) "Do you support maintaining the current arrangement of linking UT1 and UTC (to provide a celestial time reference)?"

Yes 3
No 5

2) "Do you have any technical difficulty in introducing leap seconds today?"

Yes 3
No 5

3) "Would you support the revision of Recommendation ITU-R TF.460-6?"

Yes 5
No 3

4) "If it is agreed to eliminate leap seconds within 5 years after approval of the revision of Recommendation ITU-R TF.460-6, would that create technical difficulties for your administration?"

Yes 3
No 5

The entire coherent basis of this discussion is these eight (8) "valid responses". Five for - Three against. (62%) Or is that right? Two of the yeses (plus all of the noses) apparently have no "technical difficulty in introducing leap seconds". That is - according to this poll commissioned by the proponents of the proposal - 40% of the supporters of the proposal are unruffled by the existence of leap seconds. Why then do they care?

Absence of evidence is not evidence of absence.

> Most of the ones I have talked to, admittedly mostly europeans,

> claim that this is no big deal, since they already cannot use UTC

> as Earth orientation estimator, without the fetching DUT1 and other

> earth orientation data from IERS over the internet also.

Astronomers are power users of both atomic time and solar time. The actual timescales that appear in various ways in diverse empirical investigations are derived from these in involved ways. The proposal will change how the details of the algorithms and distribution systems work. There is a significant cost to that, far beyond (in one man's educated opinion) the cost of Y2K to my community. I understand this aspect of the issue doesn't affect you personally. Why then are you arguing about it?

And, oh yeah - apparently they have similarly covert plans to deprecate TAI as well as UTC.

> For years now, we have heard your continuous thunder about how "all

> of astronomy would be badly affected", but appearantly you cannot

> even get these likely doomed astronomers to give a reasonable precise

> estimate of the impact ?

So let me understand. A mailing list is instituted to discuss precisely the issue of ceasing the issuance of leap seconds. Since this will affect systems I am responsible for (directly and indirectly), I participate in this list. You may liken email to thunder, but nothing would stop you from skipping over my messages in blissful disregard...or maybe you did, because you are misrepresenting my (indeed tediously many) arguments over the issue(s).

A number of us have pursued the task of bringing this problem to the broader attention of our community. It happens to be an obscure problem, but with broad implications. It is also the type of issue that falls in the gap between the computer science side of the community and the astronomy side of the community - a niche carved out of a niche. I am confident that the message will spread more widely as the implications become clear to more members of the community. I can't control how long that will take.

> Anecdotal evidence could seem to indicate, that might be because

> most of them found it easier to just preemptively fix the issue,

> if it even existed in the first place, than to join your sentimental

> crusade for Astronomys Proper Role In Timekeeping.

Wrongo. The world's astronomical software community, a few hundred individuals, will gather for our annual meeting in Boston in a few weeks. There are precious few of us who labor in this particular area. However, as with Y2K the broader implications of the issue will be widely felt.

I would be delighted to hear from any of those experts who carve niches out of niches out of niches regarding space-time coordinate issues who may have implemented leap-second neutral software solutions. All I know is that it ain't in any of the systems I know about.

> So yes, by now I do consider your dire forecasts of economic

> ruin unsubstantiated handwaving...

NOW WHO IS ENGAGING IN HYPERBOLE? Sorry, my thunder switch slipped...Now who is engaging in hyperbole?

> Or to put it more bluntly: You and what army ?

This nicely sums up the process over the past decade. Whereas a typical technical discussion will focus on engineering issues, it was patently obvious from the very beginning that of the five options put forth by McCarthy and Klepczynski in the November 1999 "GPS World", only the (pseudo) option of discontinuing leap seconds was being entertained.

Indeed I have no army to influence the ITU-R process. Is that really the way it should work?

Rob Seaman
National Optical Astronomy Observatory
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