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    Re: La Canoa datum
    From: Paul Hirose
    Date: 2001 Sep 26, 1:33 AM

    I did some detective work and found clues to this "La Canoa" business
    in the Explanatory Supplement to the Astronomical Almanac. The table
    of geodetic datums has this entry:
    Datum:      Provisional S. American 1966
    Ellipsiod:  International
    Origin:     La Canoa
    Latitude:   +08 34 17.17
    Longitude:  296 08 25.12
    Astronomers measure long. eastward to 360. Datum of the origin
    coordinates isn't specified in the table.
    The table of ellipsoids on the facing page has this entry:
    Ellipsoid:           International 1909
    Semi-Major Axis (m): 6378388
    Inverse flattening:  297
    An appendix in my Magellan ProMARK GPS receiver manual lists a slew of
    datums all over the world. There's no Provisional South American
    *1966* there, but there is a *1956* using the International ellipsiod.
    I used the receiver's South American 1956 datum to check Aubrey's
    WGS84 vs. La Canoa coordinates. Looked good! Latitude missed by 0.05"
    and longitude by 0.03".
    The ProMARK's South American 1956 transformation is a compromise
    giving a best fit over a huge multi-nation area. The manual's appendix
    breaks it down to smaller zones (one of which is Venezuela) and gives
    parameters optimized for each zone. These can be loaded manually for
    higher accuracy. Tomorrow (uh, later today when I wake up) I'll try
    that and report results.
    paulhirose@earthlink.net (Paul Hirose)

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