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    Re: Azimuth and Declination formulae
    From: Peter Fogg
    Date: 2005 Jul 20, 10:38 +1000

    > From: Henry C. Halboth
    > A bit more complicated, but generally employed with the Time Sight is ...
    > hav Z = sec ho x sec L x sin 1/2S - ho x sin 1/2S -L, where ...
    > Z = azimith, named according to Latitude + meridian angle, E or W
    > ho = corrected altitude
    > L = Latitude
    > pd = polar distance
    > S = ho + L + pd
    Interesting. Presumably 'hav' stands for haversine, which I vaguely recall
    is a half sine? And 'sec' is secant? I don't know what that is.
    What do I need to be able to use this formula? Scientific calculators I
    have. Do I need tables of havesines and secants?
    What is the advantage of this formula?

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