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    Re: Latitude by Lunar Distance
    From: Peter Fogg
    Date: 2006 Oct 7, 17:00 +1000

    On 10/5/06, Frank wrote:
    > I am somewhere southeast of New England, rough DR = 38N, 70W, early in
    > the morning of October 11, 2006. It's the middle of the night and a bit
    > hazy, too. The sea horizon is invisible. But I can see the Moon and
    > some bright stars... At 06:36:00 GMT I look up high in the South at the
    > Moon with Aldebaran below it. With my sextant, I carefully measure the
    > angular distance (Far limb) between the Moon and Aldebaran and find
    > that it is 11d 39.9'. Then I turn to Pollux and measure the distance
    > from that star to the Moon (Near limb this time). I find that the
    > Pollux-Moon lunar distance is 38d 13.1'. The GMT for this sight is
    > 06:39:00 exactly.
    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)
    At Lat N41d, Lon W74d, on 11 Oct 2006 (approx New York):
    GMT         Body               Azimuth        Altitude
    6h 36m     Aldebaran        132.17d        57.76d
                    Moon(Centre)   111.85          63.32
    Distance between bodies    11.37d
    6h 39m     Pollux                78.78d        31.72d
                    Moon(Centre)   112.73          63.83
    Distance between bodies    38.46d
    At the same time in New York, 3 degrees to the north and 4 degrees to
    the west, almost exactly the same angular distances. 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?
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