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    Re: Position bias from UTC
    From: Paul Hirose
    Date: 2020 Jan 8, 22:22 -0800

    On 2020-01-07 19:16, John D. Howard wrote:
    > Even though the almanac data is calculated years in advance they are not 
    printed years in advance. If the leap second was eleminated could the " MAN " 
    just print the new years almanac adjusted by one second ?  We use Long Range 
    Almanacs and almanacs four years out of date by using " fuge factors".  Could 
    one just apply an adjustment before they are printed or include information 
    for the user to take out data one second later ( or before ) ?
    It's hard to say what could be done since I have no idea of the Almanac
    lead time. It may be practical to predict ∆T well enough that UTC could
    be the time scale of the daily tables with sufficient accuracy for most
    users. But an additional correction would still be needed to realize the
    full accuracy of the tables, just as we do now.
    I don't have any bright ideas on how to distribute that correction,
    which would be the estimated ∆T used to compute the almanac, minus the
    current estimate of ∆T. You can't call the correction DUT1 since that's
    reserved for UT1-UTC.
    To be more precise, DUT1 is always a multiple of 0.1 second and is
    distributed in IERS Bulletin D, while the un-rounded UT1-UTC is called
    ∆UT. So says the Astronomical Almanac. But IERS bulletins A and B simply
    call it UT1-UTC, not ∆UT.
    If leap seconds are discontinued, DUT1 will no longer be a few tenths of
    seconds. It will grow to multiple seconds, so a different encoding
    method will be necessary in time broadcasts. Also, software will need a
    different sanity check for DUT1, as well as deletion of warnings that an
    unreasonable amount of time has elapsed since the last leap second.
    (That check is part of the IAU SOFA library of astronomical functions.)

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