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    Re: Longhand Sight Reduction
    From: Hanno Ix
    Date: 2014 Nov 25, 19:36 -0800
    Greg,

    as an aside:

    here is a simple equation for the azimuth Z.
    It is easy to derive. It might be useful when
    only the hav - table and a slide rule is available
    or resolution is an issue. Of course, the azimuth
    diagram is much faster.

    Given: D, Hc, LHA. Find Z:

    define: a = 1 - 2*hav(D);
    define: b = 1 - 2*hav(Hc); 
    define: L = a/b; 

    then:   hav(2*Z) = ( L^2 ) * hav(2*LHA);

    The Azimuth Diagram Example:
    D = 40; Hc = 20; LHA = 60;

    a = 0.7660; b = 0.9397; L = 0.8152;

    hav(2*Z)  =  0.8152^2 *  hav(2*LHA)  = 0.6646 * 0.7500 = 0.4984;

           2*Z   =  ahav(0.4984)  = 89 deg  49';
              Z                               = 44 deg  55';

    H





    On Mon, Nov 24, 2014 at 6:51 PM, Greg Rudzinski <NoReply_Rudzinski@fer3.com> wrote:

    Greg L,

    The 3x5 format is as follows:

    Latitude      L

    Declination  d                                  A                           B

                     L +/- d          Haversine  hv            Haversine hv

                     L +/- d        +Haversine  hv                         +P

                                        1- sum                      Arc Haversine sum

                                                                       Zenith Distance ZD

                     LHA              hv LHA                      Canculated Altitude Hc = 90°-ZD                                  

                                        product P = (1-sum * hv LHA)

     

    Greg Rudzinski

     


       
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