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    Re: Lunar Distance Puzzle
    From: Dave Walden
    Date: 2011 Aug 20, 19:43 -0700

    Herbert raises an interesting idea that leads to a consistency check. If the Lunar Distances from two of the stars are treated as circles of position then, of their two intersection points, one should be at the apparent position of the moon. (And one should get the same answer for each of the three pairs!) I hadn't thought of things that way.

    So, since I had a linux machine up and running, I used the topocentric-no refraction RA's and Dec's from the Xephem program with the LD's provided earlier for the no refraction case, at the solultion time and location.

    I get, using a usual two COP solver (picking the most interesting one of two intersections in each case):

    vega-altair
    -22° 47' 36.2"
    +18° 32' 40.10"

    vega-antares
    -22° 47' 36.2"
    +18° 32' 40.11"

    altair-antares
    -22° 47' 35.9"
    +18° 32' 40.10"

    while the given apparent lunar position is:

    -22° 47' 36.1"
    +18° 32' 40.10"

    I think I've understood correctly and entered all the data right.


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