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    Re: Lunar Distance Puzzle
    From: Frank Reed
    Date: 2011 Aug 14, 18:36 -0700

    Dave W., you wrote:
    "It is, as was pointed out, sensitive to refraction."

    I spent a little time trying to think this through, and I just couldn't see how it would work. I made myself a little visual model of a satellite on a known trajectory with three stars in the distance, and I could use it to get a position fix at known time or to get time given some position data (or altitudes and HP data as surrogate). But I couldn't see how you could position and time, too, as you proposed. The distance of the third star would merely be consistent with the other two. Then I tried a brute force approach generating "lunar distance lines of position" and they seemed to reach a level of closest convergence around 03:27 but there was very little change around that time. This seemed like an accidental convergence (and the LOPs did not meet presumably because I assumed it was a warm night with lower refraction). Now I see that there have been a number of comments about the sensitivity to refraction, so I have a couple of questions for you. If you set your model refraction to zero, does the solution disappear? Or in other words, is it only the variability of refraction with altitude that makes this work? Related to this, if the Moon and all three stars have altitudes above 45 degrees, is the solution worse (much more sensitive)?

    -FER

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