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    Re: GPS Timing
    From: Steven Wepster
    Date: 2002 Jul 29, 14:37 +0200

    Hi Vic,
    While doing astron navigation, an error of one second in time will give you
    a longitude error of 15 seconds of arc, since the earth is spinning through
    360 degrees in almost 24 hours. A good astro fix might have an error of 1
    or 2 minutes of arc. I think missing one or two seconds is tolerable;
    remember the old books that tought you to take a shot and then count out
    loud while stumbling back into the cabin on your way to the precious
    chronometer that hasn't been checked for three weeks.
    But, if you practice  astronav for in case GPS fails,  then you better buy
    yourself a wrist watch. I think it's preferable to keep systems separate;
    if you trust on GPS for your time signal then the breakdown of GPS implies
    the breakdown of your astro. That's bad.
    Hope this helps,
    Steven Wepster                          wepster@math.uu.nl
                                            tel +31 30 253 1531
    Mathematisch Instituut
    Universiteit Utrecht
    PO Box 80.010
    3508 TA Utrecht
    The Netherlands

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