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    Re: Noon sun fix example
    From: Hewitt Schlereth
    Date: 2009 Sep 22, 12:38 -0400

    Hi, Jeremy -
    
    Doing celestial from a ship is obviously a lot different from doing it
    aboard a sailboat. A fair number of small-boat sailors - me for one -
    would consider a 4' difference between a GPS position and a celestial
    fix pretty much OK - 4' being just a little beyond the horizon at an
    eye height of 9 feet.
    
    Anyway, the reason for the difference is that I have an aversion to
    altering other people's data. So, I took your first and last sextant
    shots as equal altitudes, even though they weren't quite. I did the
    same thing in the 'Noon Sight Shootout' a few months ago.  Just took
    George's data as presented.
    
    Attached is a work sheet where your last Hs is backed up to the time
    when it would have equalled your first Hs.
    
    That done, my longitude now comes out 0.2'  West of yours.
    
    Thanks again for the real-world data.   -Hewitt
    
    
    On 9/21/09, Anabasis75---.com  wrote:
    >
    > Hi Hewitt,
    >
    > Thanks for taking the time to do this via the table method.  I have to say
    > that I am pretty disappointed with the longitude determination from this
    > method.  4.3' is a pretty big error in my book and would send me looking for
    > math or sight errors if it happened out here.  I find it curious why there
    > is such a difference between this method and the ones Peter and I used to
    > get much more accurate fixes.
    >
    > Being unfamiliar with the book that you used, I am wondering if there is
    > some explanation as to why the results differ so greatly.
    >
    > Jeremy
    >
    > In a message dated 9/19/2009 10:06:35 A.M. Eastern Daylight Time,
    > hhew36---.com writes:
    > Hi Jeremy -
    >
    > Here's a paper-and-paper method of finding Longitude at Noon based on
    > the motion correction table published in Latitude and Longitude by the
    > Noon Sight.
    >
    > My work sheet is the .doc attachment.
    > The table scan is the .jpg attachment.
    >
    > As you'll see, this method differs from your 1300 GPS by .4' in Lat
    > and 4.3' in Lon.
    >
    > Thanks for providing data from actual combat conditions. :-)
    >
    > Hewitt
    >
    >
    >
    >  >
    >
    
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    File: 109862.ja-noon-lon-wrks.doc
       
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