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    Sextant accuracy and deflection of the vertical
    From: dpstephen
    Date: 2003 Mar 18, 14:18 -0700

    At Fred's request, here is a site where you can get information on
    deflection of the vertical and a program that will allow you to calculate
    delflection for a given location.
    The program on that web page called deflec99 calculates deflections for
    given locations.
    Unfortunately the section of the page titled "what is a deflection of the
    vertical" is under construction and not working. However as I understand it
    astronomical latitude and longitude (from sextant or theodolite) are based
    on angles related to the vertical as defined by gravity (through water
    horizon or bubble horizon) and geodetic latitude and longitude are related
    to a line normal to the ellipsoid. I beleive that GPS latitude and longitude
    are geodetic. If I am confused here please correct me.

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