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    Re: Dropping leap seconds and the impact on celestial navigation
    From: Geoffrey Kolbe
    Date: 2011 Sep 11, 08:24 +0100

    At 07:30 11/09/2011, you wrote:
    >Geoffrey Kolbe,
    >I agree with everything you said. Simple as that!
    >I have a question for you specifically. Your "Long-Term Almanac
    >2000-2050" would be impacted by this change in leap seconds. How
    >would your users be affected? Would you need to publish some sort of addendum?
    In the second edition of the LTA, it is specifically noted that the
    time system to which the ephemerides are referenced is UT1, and that
    a decision may be taken sometime during the period of validity of the
    tables to cease inserting leap seconds into UTC to keep it aligned
    with UT1. So, if DUT continues to be published as it currently is on
    the Internet, there should be no problem. If not, I may have to set
    up a transit telescope to monitor Sirius and publish my own DUT
    corrections on the Internet ;-)
    >For celestial navigation, I think the biggest concern is education,
    >both in specific instructions for dealing with any change,
    >specifically preserving the utility of textbooks and navigation
    >manuals already published, and also more generally: do we need a
    >"Don't Panic" sticker on future almanacs? I worry that there is a
    >"Pluto moment" in our future where cynicism and "The Internet Rumor
    >Mill" (also known more succinctly as "The Internet") will generate
    >endless confused accounts claiming that the IAU has ruined celestial
    >navigation --just the way they ruined the "planet" Pluto! ;) The
    >risk here is quite small. But the message can get away from us...
    You seem to imply here that the International Astronomical Union will
    make the decision on leap seconds. My information is that the
    Radiocommunications Assembly, a branch of the International
    Telecommunications Union, will take the decision about the future of
    leap seconds at their meeting in January of next year.
    Oh, and astrologically speaking, it is Neptune that rules confusion.
    Pluto rules large scale changes in society; which might well be
    appropriate as if leap seconds are abandoned, the definition of the
    "day" will no longer relate to the position of the sun in the sky, as
    it has done for all of human history to date.
    Geoffrey Kolbe

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