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communique from the leap second wars
Summary: We should make plans now about how FITS would support UTC
should the issuance of leap seconds be halted. Straw proposal: Replace all instances of "UTC" with "UT1" in the FITS standard. Begin working on a more extensive proposal for generalized time handling in keywords and tables. Discussion: For the past five years (beginning before Y2K), a group of representatives of the precision timing community have been attempting to halt the issuance of leap seconds. The effect of this would be to completely disconnect civil time, which would remain UTC in name only, from the rotation of the Earth. I won't belabor the implications of this except to note that a wide range of astronomical software and systems would have to be rewritten simply to preserve current functionality, just as with Y2K. The latest attempt is to cast this as a replacement of leap seconds issued roughly every 18 months, by leap hours issued roughly every 600 years (the effect is quadratic). One has a hard time imagining how such a standard would be enforced - Universal Time would simply cease to exist as we know it. I've appended the retroactive announcement that such a vote occurred (and the implication that they'll try again next year). If you think the IAU governs this decision, think again. There is no indication that the draft standard will ever be released for comment to the (many) interested parties, but a bootleg version is available from http://www.fcc.gov/ib/sand/irb/werit...1893wp7a/1.doc. Steve Allen of Lick Observatory provides an excellent web resource on the issues: http://www.ucolick.org/~sla/leapsecs My own take on the subject is available from: http://iraf.noao.edu/~seaman/leap Rob Seaman National Optical Astronomy Observatory --- From: Subject: [LEAPSECS] ITU Meeting last year Date: January 19, 2005 1:19:42 PM MST To: This is a very brief description of what happened at last October's ITU meeting in Geneva. A resolution was proposed to redefine UTC by replacing leap seconds by leap hours, effective at a specific date which I believe was something like 2020. This proposal was not passed, but remains under active consideration. Presumably something like it will be considered next year. My quick computation indicates that, should this proposal be adopted, it would take about a century for UT1-UTC to diverge by one minute, and many centuries before a leap-hour would be called for. I did not attend the meeting, and this is all I know. I was told the ITU web pages had essentially this same information in them, but could not find anything there with their search engine. |
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