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    Re: Bowditch long term almanac
    From: Geoffrey Kolbe
    Date: 2012 May 20, 10:20 +0100

    Yabut.... The point about tables is that all you 
    need is a pencil to get a position. And the 
    batteries never run out on a pencil, nor does a 
    pencil mind floating about in sea water. ;-)
    
    Actually, how did you arrive at that formula?
    
    Geoffrey Kolbe
    
    At 08:37 20/05/2012, you wrote:
    
    >Simply use sin d(i) = sin d(m) . sin L , where 
    >d(i) is the declination of the day , d(m) is the 
    >maximum (sun´s) declination 23 deg 27´ , and L 
    >is the longitude of the sun as measured from the 
    >closest solstice . Example : compute for the 
    >declination {at} May 20 , 2012 . Solution :
    >
    >May 20 is abt 60 days short of June 21 , or 
    >60/90 x 90 deg = 60 deg . sin d(i) = sin 23-27´ 
    >x sin 60 = 0.39795 x 0.86603 = 0.34464 => d(i) = 20.16 (20 deg 09´.5).
    >And check by the 2012 NA : the result matches 
    >May 20 , 1700 hrs UT , dec 20-09´.8
    >
    >For most navigational computations , p.e. by 
    >formulae , the accuracy is for 1 day good enough to avoid ambiguity or error .
    >
    >
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