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    Re: Longhand Sight Reduction
    From: Francis Upchurch
    Date: 2014 Jun 10, 23:05 -0700

    Oh dear. Is it time to put my beloved Bygrave away? Cant wait to here more details of the Bygrave maths.Chichester said he preferred the Bygrave when flying single handed, because he made mistakes with log tables. (Perhaps he did not have Haversines?)  But, could someone explain the main difference/advantages/disadvantages of the versine method (Vers ZD=Vers LHAxCos Latx Cos Dec+Vers(Lat+/-Dec) and the Haversine method? My versine method (Reeds Astro Nav Tables) uses tables of natural and log versines and log cos (total 11 pages).Does not need sines.

    Versine method

    log vers LHA    9.9019

    log cos Lat      9.9177

    log cos Dec     9.9642

    add              29.7838

    Nat Vers of 9.7838=        0.6081

    Lat-Dec=11013' Nat vers=0.0191. Add= 0.6272=68°6'. =ZD. 90°-68°6'= 21°54'

    Not a lot in it I would say? quicker for me than reduction tables and I understand what we are doing.

    Please correct me and explain the advantages of the Haversine over the versine. (I do not have haversines but do have versines! Where do I get haversines?)

    Bygrave. H=360°-LHA=78°21', co-lat=55°50', y(w)=64031', X=colat+y(w)=120°21', Y=180°-X=59°39', > Az =76°24'> Hc 21°54'

    No contest! Took a fraction of the time and no mistakes from looking up 4 figure logs etc. And I've got Az (OK done hundreds of Bygrave LOPs and only a couple of Versines!)

    I'll stick to my Bygrave!

     

     

       
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