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    Re: Longhand Sight Reduction
    From: Lars Bergman
    Date: 2014 Nov 26, 13:35 -0800

    Hanno Ix wrote "here is a simple equation for the azimuth Z".

    Simple? Not for longhand calculation according to me, with multiplication, division and squaring.

    A more simple formula, similar to the one used for finding altitude, is this:

    N = hav(latitude - altitude)

    P = hav(latitude + altitude)

    Q = N + P

    hav(Z) = (hav(polar distance) - N) / (1-Q)

    where polar distance = 90° - declination (if lat and dec are of same name; otherwise 90° + declination).

    The difficult part is the division with (1-Q), for very small values of Q this could be replaced by a multiplication with (1+Q).


    Lars 59N 18E


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