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    Re: Wobbly Prime Meridian
    From: Richard B. Langley
    Date: 2010 Nov 23, 17:56 -0400

    Quoting Gary LaPook :
    "WGS84 is a compromise datum that gives fairly good coordinates for
    the entire world but is not as good as the national datums"
    WGS84 is aligned very closely to the ITRF. If your waypoints, etc.,
    have WGS84/ITRF coordinates assigned then navigating with a GPS
    receiver set to the WGS84 datum is the proper approach. No compromise
    there. But if your waypoints have coordinates from some other datum
    and your GPS receiver is set to the WGS84 datum, then beware. With
    some choices of datum and grid system, you could be off by more than a
    The current North American datum is NAD83. The difference between
    NAD83 coordinates for a point and those in WGS84 is generally less
    than 2 metres.
      Richard B. Langley                            E-mail: lang@unb.ca
      Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/
      Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142
      University of New Brunswick                   Fax:      +1 506 453-4943
      Fredericton, N.B., Canada  E3B 5A3
          Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/

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