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    Re: A celestial navigation problem
    From: Antoine Couëtte
    Date: 2011 Nov 18, 07:43 -0800

    Dear Stan, and Gary


    Thanks Stan for your comments.

    As regards my "approximate answers" I have none here since I am using a 7th order regression best fit. However, I do iterate and between the first 2 successive positions, I find a distance of " d.POS=1.7 NM " (see sheet of calculations) and at the third iteration I am right on.

    Gary, certainly your approximation is excellent and very fast and powerful. And for lack of complicated software, I would have proceeded exactly the same way as you did. We both get final results within less than 0.1 NM. This is why I could recognize you so well at such a short distance !!!

    I can only claim that roundoff errors in my results are likely to be well below 0.1 NM. Any difference standing up then can be attributed to either Nautical Almanach differences(I have been using VSOP2002 to an accuracy better than 0.5 " for the Sun), and/or Sun Semi-diameter treatment (aberration / no aberration ?) and/or sight reduction (essentially dip and refraction).

    This case should also be solved very easily and accurately through 2 nd order parabolic ( or 4th order ?) best fit which in my understanding is the underlying algorithm in the software used by Peter Hakel and Andr�s Ruiz. Both should be able to get the very same accuracy final results.

    Andr�s and Peter, are you here ? :-)

    Best Regards to you all

    Kermit


    PS : How about "my pat in the back" ??? :-) + :-))


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