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    Re: Haversine- how to derive it?
    From: Samuel L
    Date: 2015 May 18, 17:36 -0700

    Hanno,

    I tried a reduction using the Haversine method Greg lists (for Deneb) on his s/v Nightcap site  (http://gregrudzinski.blogspot.com/)

    I deteremined Hc with not too much trouble but can't figure out how to calculate Zn. He shows 360d - 16d= 344

    Would you, or Greg, please explain how to determine Zn....in very simple terms?

    Thank you,

    Sam L.

     

     

    However, using the haversine G. Rudzinski and I can show you another,
    very easy calculation of Hc. Only one table, 2 pages, is used and only one
    multiplication is needed. There are no complicated sign rules
    and special cases - it will work for all permutations of  L, d and LHA.
     

    Given: L, d, LHA, find Hc. Execute these 6 elementary steps:

     
    1. calculate                 n = hav ( L - d )
    2. calculate                 p = hav (L + d )
    3. calculate                 q = p + n

    4. calculate                 n + ( 1 - q ) * hav ( LHA ); this yields hav ( ZD )
    5. find in table             ZD  by looking up the table backwards
     
    6. Finally                    Hc = 90 deg  - ZD 
     
    As can you see the steps are basic arithmetic - executable by hand in minutes.
     
    We discussed all this on the list under the topic Longhand Sight Reduction.
    For the azimuth we suggest using the azimuth table I published there, too.

     
    H   
       
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