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    Re: Differential lunars
    From: Frank Reed
    Date: 2013 Jul 31, 09:37 -0700

    Peter,

    This is a great idea. I think I would call it "on-the-fly calibration" or something like that. When I first saw your phrase "differential lunars", this was not what I was expecting!

    I think we can assume that all sextants are capable of measuring angles and the only thing in question is index error and arc error. Assuming that the lunar we are trying to measure does not sit right at a major change in arc error for the sextant we're using, then we could probably relax the constraints on keeping the star-star test angle right close to the desired lunar. For example, if I observe a star-star angle that's two degrees below the expected lunar and maybe another that's two degrees above the expected lunar and then shoot the lunar in between, I can expect to cancel out the index and arc errors at least as far as I can trust star-star angles (which is another can o' worms). If I'm up in the wee hours in the next few days (waning Moon), I will certainly try this out. Thanks for the idea!

    -FER

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