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    Re: A sextant calibrator
    From: Antoine Couëtte
    Date: 2011 Feb 14, 23:29 -0800

    RE : http://www.fer3.com/arc/m2.aspx?i=115680
    [NavList] Re: A sextant calibrator
    From: engineer---net.nz
    Date: 14 Feb 2011 15:06

    Dear Bill,

    Thank you very much for your most interesting and comprehensive reply.

    Up until your recent post about Micrometer errors, I had no idea of - or probably totally forgotten about - such kind of errors. When you earlier published your NavList Post about Micrometer errors, I went back to my Navigation Courses and did not find anything about them, while the Eccentricity errors are somewhat (overly then ???) detailed.

    Still, I now recall that during our Cruise around the World on the Helicopter Carrier Jeanne d'Arc, our Chief Petty Officer in Charge of Celestial Navigation always measured his sextant angles "from above", or "from below", whatever ...

    Reason for that ? During a previous visit in a Sextant Manufacturer's premises, he had been advised by an old sextant craftsman to do so for best achievable accuracy results. This is at least a good (counter-)example of Manufacturers and End-Users talking to each other.

    Maybe Byron Franklin also addressed this specific point to our NavList Community (Hello Byron !!!).

    This kind of "final setting/fine tuning" procedure reminds me of a similar example recently addressed on NavList - maybe in your Micrometer Errors thread after all - in which Gary Lapook (Hello Gary, too !!!) indicated that guns in turrets get best accuracy results when they are aimed at in Azimuth with this same procedure, i.e. for a given gun always "from the right" or always "from the left" to the desired Azimuth...

    No Time to dig any further into our NavList posts, but isn't this mechanical effect called "hysteresis" ???


    Enjoy your Pacific Ocean trip, and arrange to shoot as many Many MANY LOP's as you can ... you may very well become a sextant addict person this way also ...


    Thank you again and Best Friendly Regards


    Antoine M. "Kermit" Couëtte

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