[LEAPSECS] A consolidated approach.
I wisely avoided contributing the last few days' debate. Ken Seidelmann, John Seago, and I have been working to overcome the deficiencies in the process used to formulate the new ITU-R recommendation. As we said in our paper last summer, the goals are to assure that major stakeholders are included in consensus, to develop normative guidance for accommodating leap seconds should they be retained or work without them if they are deprecated, and to define in a normative sense the different flavors of seconds, minutes, weeks, etc. The guidance should include how to handle DUT greater than 0.9 seconds and what the reasonable predictive time span should be for inserting leap seconds. These I have gleaned from your exchanges are your major concerns and ideas. How are we pursuing this? We are using my authority within ISO. Several ISO technical committees are affected: ISO/TC154 (Processes, data elements and documents in commerce, industry and administration, ISO/TC12 Units and Measurement, and ISO TC37 Terminology as well as JTC-1.The terminology folks are already working on whether a time scale unconnected with astronomical events should include the term universal. I bring this to your attention to solicit your participation in resolving this long-standing issue. There will be meetings in various places, most often in Geneva. Changing the subject, the comments on geodetic references are very relevant. There is nothing like the leap second issue, but WGS-84 is not used world-wide. There are discrepancies in maps of Korea, for instance. WGS-84 is also out of date relative to the continuing examination of the geopotential such as the GRACE mission. As you all know, Earth orientation and time are not independent. Correlating EOP with real time observations in order to infer current orbits precisely enough for assessing conjunctions among satellite is very important. 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. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] A consolidated approach.
On Mon 2010-12-13T18:52:18 +, Poul-Henning Kamp hath writ: Actually, I'm pretty sure time is entirely independent of which way you orient the Earth. It is barely a decade during which the literature and nomenclature of the astronomical community has explicitly recognized that truth. Even most astronomers have not yet assimilated the new paradigm. It will be yet a while before the distinctions percolate through the operational systems and culture. Rather than add the new (and vitally necessary) concept, the ITU-R effort seeks to discard the old concept in favor of the new one with no regard for the longstanding cultural and legal applications of the old concept. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick ObservatoryNatural Sciences II, Room 165Lat +36.99855 University of CaliforniaVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] A consolidated approach.
In message 20101213190904.ga1...@ucolick.org, Steve Allen writes: On Mon 2010-12-13T18:52:18 +, Poul-Henning Kamp hath writ: Actually, I'm pretty sure time is entirely independent of which way you orient the Earth. It is barely a decade during which the literature and nomenclature of the astronomical community has explicitly recognized that truth. It is sort of ironic that the proud disciples of Copernicus have such a hard time letting go of geo-centrism ? And what happened to boldly go ? Shouldn't we discuss what we want from our timescale in the future, rather than which 30 year old computers we will need to replace ? Poul-Henning ...Who held the papertape with the ALGOL reduction programs for the PERTH70 catalog in his hands just a few days ago :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] A consolidated approach.
Poul-Henning Kamp wrote: Actually, I'm pretty sure time is entirely independent of which way you orient the Earth. Well, Ernst Mach and Albert Einstein might be among those who quibble :-) Threads on this mailing list (and the original Navy list) have often made an implicit assumption that time is some Platonic ideal. Rather, whether a timescale is atomic or layered on Earth orientation or some other phenomena, ultimately the clock in question relies on some measurement process. Our society certainly equates time with time-of-day. My point being that this list is for discussing the requirements for civil timekeeping, not some esoteric technical timescale. This is an engineering question, not philosophy. (Irrelevant digressions about apparent timescales directed to /dev/null.) We have any number of degrees-of-freedom available for tweaking. Completely disconnecting civil time from time-of-day is not one of the possibilities. Leap seconds are a mechanism for synchronizing with time-of-day. There are other possible mechanisms. It is not the members of this list (any of us) who have demonstrated an unwillingness to consider all the actual possibilities. Shouldn't we discuss what we want from our timescale in the future, rather than which 30 year old computers we will need to replace ? Of course. We could have been discussing any number of interesting questions rather than spending 10 years fending off a badly designed proposal that is pursuing an inane hidden agenda. That said, any world-scale re-engineering project had better include requirements derived from legacy systems. Rob ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
