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Hi Peter, you wrote:
"Here are the calculated OBSERVED altitudes and azimuths of the
stars and the Moon. The distances between the bodies has then been
calculated.

At Lat N38d, Lon W70d, on 11 Oct 2006 (at sea):
GMT         Body               Azimuth        Altitude
6h 36m     Aldebaran        134.62d        62.06d
                Moon(Centre)   110.68          67.34
Distance between bodies    11.41d
6h 39m     Pollux                79.04d        34.18d
                Moon(Centre)   111.62          67.88
Distance between bodies    38.47d


(Frank's distances were 11d 39.9m and 38d 13.1m) "

First, you calculated the altitudes and azimuths at the DR. The final
fix is quite some distance from the DR. Second, you are apparently
working only to the nearest 0.01 degrees. That's much too coarse. You
should re-do the calculations working to the nearest 0.0001 degrees.
Then differences of 0.1 minutes of arc are much more likely to be
correct. Also, please note that the observed distances I quoted (and
yes, they ARE correct) were distances from the Moon's limb to the star,
not the Moon's center.

And you wrote:
"As would be expected. The small differences are thought to be due to
parallax and refraction, not the change in position. How can position
be determined from these observations? "

Ah, but Peter, the difference in parallax IS due to a change in
position. That's why this works. :-)

-FER


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