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    Re: Lunar Occultation continued...
    From: Paul Hirose
    Date: 2015 Nov 06, 12:53 -0800

    On 2015-11-05 0:12, I wrote:
    > I checked lunar distance at
    > the given position and times with my Lunar3 program. Assuming the times
    > are UT1, at immersion [21:49:49] I have lunar distance -0.0002° to Aldebaran. At
    > emersion [22:48:24] it's +0.0003°.
    
    After recalculating with a more accurate semidiameter, those lunar
    distances decreased by .0001°, to -.0003° and +.0002°.
    
    Since Bob Crawley mentioned the effect of Earth's oblateness, I tried a
    spherical Earth with the same latitude, longitude, height (zero), and
    equatorial radius. The new lunar distances were +.0027° and .0000°. The
    last is not a typo. Apparently the geometry is such that the difference
    between a sphere and an ellipsoid is insignificant at emersion time.
    
    I also calculated the coordinates (on the GRS80 ellipsoid) that put the
    observer at the same point I got with a spherical Earth. The actual
    coordinates of Orwell Observatory are on the upper line.
    
    N52 00.6 E001 13.8      0 m
    N52 11.8 E001 13.8 +13300 m
    

       
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