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Subject: Re: Sextant Positions versus Map Datums?
WSMurdoch@XXX.XXX
Date: Fri Jan 18 2002 - 13:28:55 EST
Aren't we missing the original question ?
> How does the WGS84 ellipsoid compare with the astronomers one?
From the coordinates systems section of the website mentioned earlier:
http://www.colorado.edu/geography/gcraft/notes/coordsys/gif/difsys.gif the position of the star in the hand of the Goddess of Liberty atop the capital dome in Austin, Texas is:
NAD 83 -- 30:16:28.82N, 97:44:25.19W
NAD-27 -- 30:16:28.03N, 97:44:24.09W
WGS-72 -- 30:16:28.68N, 97:44:25.75W
If I were to climb to Libery's shoulder, sit on the star, and determine my position with a sextant, a bowl of water, the Nautical Almanac, sight reduction tables, and the heavens (and do it perfectly), what would the position of the star be ?
If I were to do the same from every point on the surface of the earth, where would I find the greatest deviation from the position determined by a GPS set to (say) WGS84 ?
Bill Murdoch
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