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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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