Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: Longhand Sight Reduction
    From: Hanno Ix
    Date: 2014 Nov 25, 19:36 -0800

    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';


    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


    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site