RE: Geodetic precision

From: Matson, Robert (
Date: Fri Aug 17 2001 - 10:55:57 PDT

  • Next message: Ed Davies: "Re: Geodetic question"

    Hi All,
    Ed Davies wrote:
    > I'd strongly urge the use of WGS-84 whereever high precision is
    > required.  Apart from it being the basis of GPS and pretty much the
    > world standard it also has the advantage that the least badly defined 
    > transformations between datums exist with respect to it.  Most 
    > transformations between other datums go via WGS-84 anyway.
    In case anyone cares, SkyMap and IRIDFLAR have always
    used WGS-84.  So if the orbital elements used with SkyMap
    or IRIDFLAR are WGS-72 (or some other datum), then that
    will introduce a small systematic error in the predictions.
    Likewise, if you supply SkyMap or IRIDFLAR with observer
    coordinates in a datum other than WGS-84, that will also
    introduce an error (primarily in longitude).  The maximum
    positional error between these two datums occurs at the
    equator, with a longitude difference of 17.1 meters (or
    about .00015 degrees) and a latitude difference of
    4.5 meters (.000040 degrees).  The longitude error is
    always .00015 degrees, but in terms of meters it is
    17.1 * COS(Latitude).
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    This archive was generated by hypermail 2b29 : Fri Aug 17 2001 - 10:59:05 PDT