[LEAPSECS] LEAPSECS Digest, Vol 48, Issue 12

Finkleman, Dave dfinkleman at agi.com
Wed Dec 15 12:47:38 EST 2010

Many of your comments are addressed in AIAA-2010-8391, which Ken, John,
and I wrote for the Toronto AAS conference last August. It is available
online, or interested parties can write me personally, and I will
provide copies. AGI did not relinquish complete copy rights to AIAA or

ISO 8601 is a problem. So far I have not heard anything from ISO TC12,
which is responsible. But I am diligent. I will extract something from
them. Their treatment of time is "deficient" and inconsistent. I don't
know how this was coordinated either. Most of their treatment of time
is just vetting almost every possible way of expressing the digits.

I really like Duncan Steel's book, Marking Time. It may not meet the
standards of time professionals, but it is readable and understandable.
Dennis and Ken provide a wealth of well referenced material as well.

There are, of course, many time scales. Our paper discusses this
briefly. Which one uses depends on the application. In my experience,
astrodynamics is the same. Different force models, solution techniques,
and computational implementations. Some better for some applications
than others. None universally suitable for everything. In that
discipline, we (CSSI) feel it important that one understand the
differences among the techniques so that different outcomes can be
explained and the best technique chosen by the user for his needs. We
strongly believe that there should not be a "universally" mandated
approach. The same for time scales, I think.

ISO is not a governmental organization. It does not enforce and it
cannot mandate any of its standards. The standards are developed
voluntarily by experts WITH A STAKE IN THE OUTCOME and who
represent balance among industry, research, academia, and government.
ISO standards are not recommendations. They are "normative" consensus.
In that regard, ITU has no normative or legal authority. In fact, what
credibility ITU has in standards resides in ITU-T, not ITU-R!

BIPM, CIPM, etc. are pivotal. They participate in JTCTG-1, which I
mentioned briefly. I won't go into what JTCG-1 is in email, but it is
the evolved metrology community, composed of literally dozens of
stakeholder organizations.

Enough for the moment.

Dave Finkleman
Senior Scientist
Center for Space Standards and Innovation
Analytical Graphics, Inc.
7150 Campus Drive
Colorado Springs, CO 80920

Phone: 719-510-8282 or 719-321-4780
Fax: 719-573-9079

Discover CSSI data downloads, technical webinars, publications, and
outreach events at www.CenterForSpace.com.

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