On Fri, Mar 16, 2018 at 10:16 AM, Matsakis, Demetrios N CIV NAVOBSY, N3TS < demetrios.matsa...@navy.mil> wrote:
> I was surprised to find phrases in the Lick web pages: "CCIR ignored the > advice that astronomers " and "squelched astronomers who insisted that leap > seconds would cause trouble". > > I realize their author is not the only person with a strong emotional > bias, but even so I question the tone of these web pages because they are > inconsistent with the following: > > 1. There was a progression in thought as technology advanced and atomic > clocks proved their reliability. > > 2. It should be obvious that ephemeris time would need a flywheel system > to get practical time to the users, and GMT could be part of that. Today > individual labs realize UTC(k) for the same reason - to flywheel before the > monthly computations of UTC are published. WWVB, GPS, and your local cell > towers are all part of the system as well. (Even so, I think everyone > today agrees that Ephemeris time was a mistake.) > > 3. According to references in Nelson et al’s Metrologia article, which > was peer-reviewed, it looks to me like the switch to UTC was by universal > agreement among the institutions. The IAU, URSI, CIPM(=CGPM), and CCIR(= > ITU) all agreed to the current system in the late 60's, and I would guess > that the timing of their resolutions probably depended more on the > (generally) 3-year spacing of their general assemblies than anything else. > Note that many of those groups had overlapping membership. It would > however be unusual if all individual members of these bodies ever agreed to > any resolution, even if passed "by consensus". > The adaptation of UTC was by consensus. The leap second stuff was a rush job in 1971 with the first leap second on Jan 1, 1972. I think that rush job is what the Lick pages refer to. For more trivia, the dynamic Gernot Winkler of the USNO was both a > practical clock man and astronomer. He was not the only one, and he was a > very active member of the IAU who chaired commissions, served on working > groups, etc. He told me personally that he and Essen independently came up > with the idea of leap seconds. He also said a big reason was to win the > support of the mariners, who in the pre-GNSS days actually did celestial > navigation and who in the pre-internet days could not easily get access to > tables that incorporated the difference between UT1 and UTC. > UT1 - UTC was known to .1s based on WWV and other broadcasts. At the time, the < 1s error was so that you limited your error in navigation to something acceptable. Though one also had LORAN-C (which had it's own time-scale based on UTC w/o leapseconds to compute the TOCs, but whose operational bases had atomic clocks set to UTC). Warner > To: Leap Second Discussion List > Subject: [Non-DoD Source] [LEAPSECS] D.H. Sadler in 1954 > > In 1954 D.H. Sadler produced a monograph on the changes in time > that had been resolved at the 1952 IAU General Assembly. > His writeup is clearer than almost anything else for the next 60 years. > It was published in Occasional Notices of the RAS, and it has been hard > to find until now. > https://www.ucolick.org/~sla/leapsecs/twokindsoftime.html > This is one of the series of documents produced starting in 1948 and > proceeding through the next 20 years where astronomers explained that > two kinds of time would be needed to satisfy all applications. > > -- > Steve Allen <s...@ucolick.org> WGS-84 (GPS) > UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat > +36.99855 > 1156 High Street Voice: +1 831 459 3046 Lng > -122.06015 > Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m > _______________________________________________ > LEAPSECS mailing list > LEAPSECS@leapsecond.com > https://pairlist6.pair.net/mailman/listinfo/leapsecs > > _______________________________________________ > LEAPSECS mailing list > LEAPSECS@leapsecond.com > https://pairlist6.pair.net/mailman/listinfo/leapsecs >
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