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    Re: Navigation without Leap Seconds
    From: Bill Noyce
    Date: 2008 Apr 18, 15:54 -0400

    Leap seconds correct for variations (mostly the slowing down) in the
    rate of the Earth's rotation.  I think everything else that's an input
    to the Nautical Almanac tabulations -- the Earth's orbit around the
    sun, and also the other planets, the Moon's orbit around the earth,
    proper motion of the stars, etc. -- is computed from the free-running
    time that ignores leap seconds.  In a way, we're still clinging to the
    pardigm used in the Almanac's early days, when things were tabulated
    by Greenwich Apparent Time.  Fortunately for navigation, and for
    Geoffrey's long-term almanac, most celestial objects don't move very
    much in a few seconds.  Thus, for practical navigation, it doesn't
    matter whether we use UTC or the free-running clock for their
    positions.  It *does* matter when we go to translate those positions
    into GHA.
    
    To answer the question that started the thread, I think future
    navigators will compute a position, then adjust their longitude.  That
    uses (marginally) better positions for the celestial objects than the
    alternative, which would apply a sort of "equation of time" before
    looking up positions.
    
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