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    Re: Moon's 4SD
    From: Bill B
    Date: 2006 Nov 02, 03:34 -0500

    Alex wrote
    > It remains to explain why star and Sun tests give
    > consistently
    > smaller IC than the Moon test (at least in my measurements).
    > It is interesting how various authors rate the
    > various tests
    > for IC in the order of decreasing precision.
    > Heath (of Hezzanith): Star, Horizon, Sun.
    > Russian manual: Sun and Star equally good, then Horizon.
    > (They quote the statistics that the typical
    > accuracy of the Sun/star test is 0.1 to 0.2, while
    > the Horizon gives only 0.5.
    I surmise it eventually becomes a one-man-dog.  What works for one person
    may not work for another human being.  I am horrible at one star IE checks.
    Good sun IE checks usually have a sigma equal to the horizon IE checks, but
    the values vary due to (I firmly believe) problems with astigmatism with my
    naked eye.
    As an undergrad psych major I can prove that input is usually a long way
    from final perception.  That includes classes and labs on the optical
    I do agree with your assessment of moon IE checks.  I feel it is both a
    harder target in terms of edge definition and axis, as well as a challenge
    to my astigmatism.  I can measure horizontal vs. vertical sun differences,
    but have no clue what is happening when I tilt the sextant to do a moon IE
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