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    Re: Refraction, Cassini model
    From: Paul Hirose
    Date: 2018 Nov 28, 15:33 -0800

    On 2018-11-27 18:45, Roger W. Sinnott wrote:
    > By the way, the latest (3rd ed., 2013) of the Explanatory Supplement to the 
    Astronomical Almanac, on pages 277-280, gives a number of methods for finding 
    the atmospheric refraction.  Along with several low-accuracy formulas, it 
    describes a precise algorithm for calculating refraction using numerical 
    integration.  This method is written out in clear steps, like the outline of 
    a computer program.
    That last sounds like the algorithm in the 1992 Explanatory Supplement.
    Andrew Young (not Bruce Young as I originally wrote — thank you for the
    correction) criticizes its refractive index formulas:
    "Unfortunately, this incorrect and obsolete formula was also used by
    Hohenkerk & Sinclair (1985), from which it was copied in the new (1992)
    edition of the Explanatory Supplement (see the middle of p. 142 for the
    obsolete formula there); so we can expect to continue to see it crop up
    again in the future."
    The 1985 Hohenkerk and Sinclair work was Nautical Almanac Technical Note
    63, "The computation of angular atmospheric refraction at large zenith
    Young notes some issues with that document:
    In the Technical Note I discovered some trivia about the Nautical
    Almanac: the low altitude refraction table was computed with the 1944
    model of Garfinkel:

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