NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Bowditch long term almanac
From: Geoffrey Kolbe
Date: 2012 May 20, 10:20 +0100
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 @ 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 . > > >---------------------------------------------------------------- >NavList message boards and member settings: www.fer3.com/NavList >Members may optionally receive posts by email. >To cancel email delivery, send a message to NoMail[at]fer3.com >----------------------------------------------------------------