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    Re: Latitude by Lunar Distance
    From: Frank Reed CT
    Date: 2006 Oct 07, 17:09 -0700

    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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