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    Re: Latitude and Longitude by "Noon Sun"
    From: Fred Hebard
    Date: 2005 Jun 5, 11:42 -0400

    On Jun 5, 2005, at 10:50 AM, George Huxtable wrote:
    > I ask nav-L members if they would be happy to cross on ocean, without
    > GPS,
    > with a "navigator" who had learned his craft in that way, and was
    > unable to
    > handle any other observations than those of the Sun at noon. That's
    > what I
    > fear will happen, if such individuals can claim some qualification in
    > "celestial navigation".
    In response, I don't find the intercept method any more difficult to
    understand geometrically than a noon shot.  The basic flag pole
    analogy, much derided here, seems adequate to me, only requiring that a
    spherical surface and infinitely tall pole be substituted to achieve
    reality.  While building the infinitely tall pole, an instructor would
    get to talk about parallax.
    Using pen and paper methods of sight reduction, LOP navigation is more
    difficult, but not with a calculator or computer.  Also, using the Air
    Almanac, LOP sight reduction on paper is much easier than the Nautical
    Almanac/HO-229 or predecessors.  The Air Almanac seeks 1.0' precision
    while the Nautical Almanac seeks 0.1' precision.
    George's comments about taking a prolonged series of sights while
    underway are well taken.  Not only would it take a long time to take
    the shots, but a clear sky is needed.  Why not take a quick morning,
    noon and evening shot?
    One point about a traditional noon shot is that the sun often peaks out
    from behind the clouds at noon for a few moments even on days with
    heavy overcast.  There is a story famous to me about a passenger on a
    ship asking why all the officers had their sextants out under a cloudy
    sky at noon, only to be informed by the captain that the sun often
    would peak out for a bit, and sure enough it did.  That's also been my
    experience at 36N in the mountains.

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