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    Re: Longhand Sight Reduction
    From: Hanno Ix
    Date: 2014 Nov 23, 10:10 -0800
    Greg,

    there is a form of the hav-Doniol some people might prefer.
    Mathematically, there is no difference to the original formulation.
    Here it is:

                   define:   N  =  hav( L - D );

                   define:   P  =   hav( L +D );

                   define:   Q  =  N + P;

           

                   hav(s2s)  =  N + ( 1 - Q )* hav(LHA);


          Example 

           L =10; D = 20; LHA = 40. To find s2s.


           N = 0.0076;   P = 0.0670;    Q = 0.0746;


           So   hav(s2s)    0.0076 + (1 - 0.0746) * 0.1170; 

                           =  0.1158;

           and    s2s       ahav(0.1158        39deg 48';

           or      Hc      =  90 deg - 39deg 48'  =  50deg 12';



    H






       
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