[LEAPSECS] IAU UTC report

[Rob Seaman]

On Nov 6, 2014, at 10:19 PM, Alex Currant via LEAPSECS <leapsecs at leapsecond.com> wrote:

> I am sorry but my statement was correct:  the IAU has not taken a stand.

That wasn't your complete statement.  You went on to speculate "if it were so simple then the disagreements that were expressed in the IAU deliberations would not have been sufficient to prevent a resolution."  Rather, the working group deliberations produced a unified report signed by all members including Dr. Arias:

	http://hpiers.obspm.fr/eop-pc/earthor/utc/report_WG_UTC_2014.pdf

The terms of reference for the working group included:

“Responding to the proposal of recommendation to establish a continuous reference timescale under the International Telecommunication Union, this  working group will discuss about the redefinition of UTC from the perspectives of IAU”

To the extent that the IAU has a perspective on this issue, the working group report expresses it.  It is not accurate to say that the IAU has not taken a stand, rather the working group was split between two strong positions about continuing leap seconds, but the entire working group agreed that 'in the event of the deletion of future leap seconds the name of the scale should no longer reference the astronomical time scale “Universal Time”'.

> My statement was correct because an IAU Working Group is not the IAU, and that IAU leadership has been explicitly clear about this point.

Speculation about the intentions of the IAU is unwarranted.  One cannot simultaneously argue that the IAU has not taken a stand while saying that the IAU leadership's intentions are explicitly clear.

> Similarly, it appears you have distorted the Torino meeting by suggesting a consensus existed.  The summary of that meeting, as referenced on Steve Allan's web pages for example, specifically states that there was no concensus, yet you claim one existed.

As with the IAU UTC working group, the consensus of the Torino meeting was split on the question of whether the status quo should be maintained.  However, as with the report of the IAU working group, the closing summary report of the Torino meeting:

	http://www.ucolick.org/~sla/leapsecs/torino/closure.pdf

expresses (verbatim) conclusions including the "preferred characteristics of a potential alternative" as below:

Objectives :

	• To address the future of the Leap Second and related issues.
	• To draft a recommendation on the next steps on this issue to WP7A of the ITU-R.

Conclusions:

	• There was no overwhelming consensus on a whether the status quo should be maintained or an alternative should be pursued.
	• However, the preferred characteristics of a potential alternative emerged (see below).
	• This draft alternate proposal should be passed on to WP7A for detailed development of an

Opinion to be transmitted to the appropriate international organizations.

	• Advances in technology in communications, navigation and other fields would be enhanced in their interoperability by the adoption of a single, internationally recognized time scale for use in civil, engineering, and scientific applications.

Draft Alternate Proposal :

	• Evolve from the current UTC Standard by transition to Temps International (TI) (2022 – 50TH anniversary of the UTC time scale). The date suggested is influenced by the lifetimes of existing systems that would be expensive to change.
	• TI should be a continuous atomic time scale, without Leap Seconds, that is synchronized with UTC at the time of transition.
	• Responsibility for disseminating UT1 information should remain solely with IERS.

Rob Seaman
National Optical Astronomy Observatory
--

> From: Rob Seaman <seaman at noao.edu>
> To: Leap Second Discussion List <leapsecs at leapsecond.com> 
> Sent: Thursday, November 6, 2014 10:45 PM
> Subject: [LEAPSECS] IAU UTC report
> 
> On Nov 6, 2014, at 8:04 PM, Alex Currant via LEAPSECS <leapsecs at leapsecond.com <mailto:leapsecs at leapsecond.com>> wrote:
> 
>> The IAU has not taken a stand on this - if it were so simple then the disagreements that were expressed in the IAU deliberations would not have been sufficient to prevent a resolution.
> 
> 
> This is not correct.  The IAU UTC working group did take a carefully negotiated stand on this.  All members of the working group contributed in a serious and professional manner, and I was honored to work with all of them, including those whose opinions differed from my own.  The final report from the IAU UTC working group is available online from the scrolling news banner at the top of the page:
> 
> 	http://hpiers.obspm.fr/eop-pc/ <http://hpiers.obspm.fr/eop-pc/>
> 
> From the executive summary:
> 
> "Consequently, the Working Group recommends that the IAU respond to the ITU-R by stating that the IAU is not in a position to formulate a conclusive opinion regarding any change in the definition of Coordinated Universal Time. Nevertheless, in the event of the deletion of future leap seconds the name of the scale should no longer reference the astronomical time scale “Universal Time” to avoid technical confusion, and a time interval of at least five years between adoption and implementation should be allowed."
> 
> This supports the consensus from the 2003 Torino colloquium.  Whether a large organization like the IAU or ITU responds efficiently to such a recommendation depends on many factors, but nothing about the report was "sufficient to prevent a resolution" or to prevent forwarding it to the ITU, and the report was delivered to the IAU Exec in a timely fashion.
> 
> Rob Seaman
> National Optical Astronomy Observatory

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