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    Re: refraction calculation
    From: Antoine Couëtte
    Date: 2010 Apr 3, 01:16 -0700

    Dear Sir,

    So, ...

    ... You are "THE" M. G.G. Bennett quoted many times in Astronomical work and in particular in M. Jean Meeus's celebrated "ASTRONOMICAL ALGORITMS" ...


    In "Astronomy and Astrophysics" 278, 659-664 (1993) "Determination of atmospheric refraction from the distortion of the Sun's disc" by M. L. Györi, there is a very interesting study which carefully reviews the values given by your own formula and rates it as absolutely excellent !

    I am - as all of us are - quite impressed !


    In your enclosed letter, I just discovered that you also worked a single "backwards" formula (i.e. from true/unrefracted to apparent/refracted) which I was not aware of earlier.

    The only other "backwards refraction formula" I know of can be found in this same book and is credited to M. Porstein Saemundsson from the University of Iceland.

    So, I will soon take the time to compare them both.

    The great interest of such formulae is that they can be adequately derived over the whole range of the height variable and they give you most continuous derivative values throughout, which is sometimes very nice for some computations.

    Thank you for joining us, and thank you for sharing your experience and expertise with us !


    Happy Easter and


    Best Regards


    Antoine M. "Kermit" Couëtte

    antoine.m.couette at club.fr

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