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    Re: Lunar Distance Puzzle
    From: UNK
    Date: 2011 Aug 21, 15:24 +0000

    Dave,
    
    When I compute the distances from the app. Moon position that you are 
    giving below to the three stars in question, I obtain results that 
    differ by up to 8" from the distances that you posted on 8/16 in your 
    "refraction-free" problem. Unless I am making a bad mistake in my 
    calculation, my star ephemeris must differ substantially from yours. I 
    find both alternatives equally disturbing. Would you please post the 
    positions of the three stars (whether geocentric or topocentric for the 
    solution - it does not matter.)
    
    I obtained from MICA:
    
    Altair                  19 51 23.125          +  8 54 05.51
    Antares             16 30 09.432          - 26 27 28.66
    Vega                 18 37 22.186          + 38 47 49.42
    
    Thanks,
    
    Herbert
    
    
    
    
    On 2011-08-21 02:43, Dave Walden wrote:
    >
    > 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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