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    Re: Problem with a sextant
    From: Alexandre Eremenko
    Date: 2006 Apr 25, 08:50 -0400

    On Tue, 25 Apr 2006, Bill wrote:
    > In the global overview, we (you and I at least) are striving for a 0.1' to
    > 0.2' intercept with a static land-based environment. I am not clear the
    > nautical almanac coupled with sextants represent a system that can achieve
    > that accuracy repeatedly.
    My goal is somewhat narrower. I don't care about almanach, reduction,
    etc. All this can be done very precisely (Using Astronomical Almanac,
    for example etc.) I also do not preset any target numbers like 0.2'.
    My question is: what is the real accuracy of my instrument, coupled
    with my ability to use it?
    And what is the real accuracy of the best sextants.
    Whatever it is I would like to discover it with my own experiments.
    It is not the MAGNITUDE of the errors which frustrates me so
    much in this case. It is that they are all of the SAME SIGN!
    It is a SYSTEMATIC error whose reason I don't understand.
    I hardly EVER made a signle undershot in these years!
    THIS is really frustrating, not the magnitude of the errors.
    If a little speck somewhere on the arc causes this,
    then SNO-T and Freiberger is just a poor design.
    Because on your Astra you could inspect the worm with
    a magnifying glass, and discover the speck, and with the stupid enclosed
    I cannot do this.

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