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    Re: That darned old cocked hat
    From: Jeremy C
    Date: 2010 Dec 13, 23:53 EST
    George wrote:
     
    In a message dated 12/11/2010 1:05:20 A.M. Central Asia Standard Tim, george@hux.me.uk writes:
    John Karl writes-

    "Next we acquire three LOPs.  They do not intersect at a common point.  We
    don’t know where the true fix is."

    Let's say we do. Take an anchored vessel at a precisely known location, say
    by GPS.

    Measuring the altitude of a star does not alter that location. The
    probability of the observation being towards or away depends only on the
    random scatter of the observation itself, being precisely 50:50.
     
    I guess it matters how precise we want to be.  I've had numerous observations with less than a 0.05' intercept and I assumed they were neither towards nor away and would draw them directly through my AP.  I've even had a time or two where I've had 2 stars in the same twilight have no effective intercept.
     
    Of course I rarely shoot only 3 bodies (5 times in my long voyage of 2009, mostly due to clouds) so I always end up with a multitude of cocked-hats to try and figure out, but that is another story.
     
    Jeremy
       
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