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    Re: Instumental error?
    From: Bill B
    Date: 2005 Apr 20, 15:38 -0500

    > Alex you wrote:
    > "25      38    51    65    68    71     82    90    127
    > -0.5   -0.4  -0.4  -0.6  -0.2  -0.1   -0.2  -0.2  -0.8
    > Frank responded
    > Should I attach this table to my sextant box lid as a
    > certificate, and use it?"
    > I would. How do you feel about the large jumps in the table from 65 to 68 and,
    > less so, from 90 to 127?
    I would not attach this table to my sextant box lid as a
    certificate.  I concede your hand is more steady than mine, your experience
    (and logs) with your sextant far greater than mine, and your observation
    methods and statistics are close to flawless as is humanly possible.
    And as you pointed out (paraphrase), the tougher the shot, the higher the
    standard deviation.  I find my usual standard deviation with the sextant in
    a comforatable position to be < 0.2'.  In extremely awkward positions it may
    rise to 0.6'.  Pretty bad.
    I have two observations:
    1.  It seems the SNO-T is a high-quality instrument.  If I recall, the specs
    are plus/minus 10 seconds error along the arc (0.17').  Unless you got a
    dud, any value higher than 0.2' is highly suspect.
    2.  Are you using the same star pairs when you get the 0.5', 0.6', and 0.8'
    values? If so, could the results indicate some type of personal error in in
    that position.
    Think we need to get together in a more controlled setting with fresh eyes
    and do some comparisons, using the same scope on both instruments.

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