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    Re: Moon sight?
    From: Bill B
    Date: 2014 Oct 05, 15:50 -0400

    On 10/5/2014 12:31 AM, Sean C wrote:
    > Would you please explain to me the formula you use for Refraction and
    > where you got the figures? The 7.32 and 4.32.
    Sorry about the my answer. Off base as I commingled two of my projects
    in my memory.
    The  7.32 and 4.32 are very similar in value to those used in Bennett's
    simple formula on page 106 of Meeus's "Astronomical Algorithms," but the
    formula's differ.
    Bennett's formula is:
    R (in arc minutes) = 1/tan (ho + 7.31/ho + 4.4)
    ho = apparent altitude = Ha
    Bennetts's formula from Wikipedia
    R=cot(ha + 7.31/ha+4.4)
    As Bennett's is referred to as a "simple empirical formula," and Bennett
    gives two methods of refining the results, I would surmise the NA
    version is more rigorous.
    Bottom line, this does not answer you math/physics question of how the
    constants and formula's were derived. Some of the list Guru's may help
    out there.

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