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    Re: Sextant shot accuracy
    From: Gary LaPook
    Date: 2012 Aug 21, 12:57 -0700
    At least now I know where the conclusions came from. I am attaching a 1957 article from the Journal of the Institute of Navigation which contains those conclusions. Read it for yourselves, you can assess their methodology for yourselves.  I may have posted it before but I couldn't find it on the site.


    --- On Tue, 8/21/12, Antoine Couëtte <antoine.m.couette@club-internet.fr> wrote:

    From: Antoine Couëtte <antoine.m.couette@club-internet.fr>
    Subject: [NavList] Re: Sextant shot accuracy
    To: NavList@fer3.com
    Date: Tuesday, August 21, 2012, 8:49 AM

    Hello Jeremy,

    I was about to write exactly the same remarks as yours ...

    Before GPS, some of (very few of) us had access to Transit, which was accurate enough to grade sextant fixes accuracy, and apart from it - sometimes Loran C, or even Racal (in very limited areas) - there was no way to reliably and consistently assess accuracy of Celnav Fixes anywhere on Earth.

    100 % agree with you on the importance of having a sharp and well defined horizon. I would just add : observe as close as possible from the surface - when and if achievable - at the lowest height from which the waves and swell are not visible/appreciable at horizon distance. And even though, do not hesitate to average observations : 5 is my magic number, because in 4 minutes or so, ANY height is absolutely linear with time to an accuracy of 0'035 ...

    An excellent horizon, with an excellent sextant your cherish, maintain and trust ? Yes, you can get a Celnav Fix within 0.2 / 0.3 NM of GPS position. Be very careful with your time recordings then ! Just that simple ... with a bit of luck though, but sometimes luck is to be deserved !

    Some of our Readers will already have noticed that Sextants are (to be treated) like Ladies then ... :-)

    Best Regards from

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