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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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