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    Re: Longhand Sight Reduction
    From: Hanno Ix
    Date: 2014 Jun 9, 12:24 -0700

    you are obviously attracted to the long-hand thing too, right?
    And it is a nice challenge. You answered it with a rather
    compact RIC ("Rudzinski Index Card").

    Peter used a  multiplication-by-hand technique that calculates only significant digits.
    I never could come up with one I liked. Peter's looks very good but I don't
    see all the detail behind it yet. Do you know it?
    Using it on today's RIC might render it even more compact.

    And for Peter: could you elucidate your method in detail, please?


    On Mon, Jun 9, 2014 at 9:11 AM, Greg Rudzinski <NoReply_Rudzinski@fer3.com> wrote:

    The attached index card shows a sight reduction done longhand to 4 places using cosine and haversine tables. This is a manageable method for those who want to avoid logs. The beauty of the haversine table as presented in Bowditch is that LHA can be directly entered and formula rules are simple. 

    hav z = hav(L~d) + cosL cosd havLHA

    Hc = 90 - z  

    L-d same name

    L+d contrary name

    A compact set of cosine haversine tables, Ix diagram, and LTA would make a nice sextant box booklet. The question now is can a 10" sliderule sight reduction do a better job if scaled with haversines ?

    Greg Rudzinski


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