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Re: Longhand Sight Reduction
From: Hanno Ix
Date: 2014 Nov 23, 10:10 -0800
From: Hanno Ix
Date: 2014 Nov 23, 10:10 -0800
Greg,
there is a form of the hav-Doniol some people might prefer.
Mathematically, there is no difference to the original formulation.
Here it is:
define: N = hav( L - D );
define: P = hav( L +D );
define: Q = N + P;
hav(s2s) = N + ( 1 - Q )* hav(LHA);
Example:
L =10; D = 20; LHA = 40. To find s2s.
N = 0.0076; P = 0.0670; Q = 0.0746;
So hav(s2s) = 0.0076 + (1 - 0.0746) * 0.1170;
= 0.1158;
and s2s = ahav(0.1158) = 39deg 48';
or Hc = 90 deg - 39deg 48' = 50deg 12';
H
