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    Re: Sextant frames
    From: Brad Morris
    Date: 2009 May 13, 09:25 -0400

    Hi Bill
    Thanks for confirming what should be the standard mode of operation.
    Naturally, there are two sources of heating.  One is the radiated energy being 
    applied by the rays of the sun. The other is the atmosphere surrounding the 
    sextant.  If we wanted to analyze the sextant just for radiated energy, we 
    would place the sextant in a vacuum chamber and apply radiated energy.  Hard 
    to operate in the vacuum, but it would separate out the ambient energy from 
    the radiated energy.
    What your test shows is that the caution about warming a metal sextant out of 
    the rays of the sun is perhaps a bit over the top.  The distortion of a metal 
    frame, just as theorized, is negligible.
    Perhaps you can perform the same experiment with a plastic sextant, where the 
    warming of the radiated energy would predominate over the ambient energy.
    Best Regards
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