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Re: Longhand Sight Reduction
From: Hanno Ix
Date: 2014 Nov 25, 19:36 -0800
From: Hanno Ix
Date: 2014 Nov 25, 19:36 -0800
Greg,
as an aside:
here is a simple equation for the azimuth Z.
It is easy to derive. It might be useful when
only the hav - table and a slide rule is available
or resolution is an issue. Of course, the azimuth
diagram is much faster.
Given: D, Hc, LHA. Find Z:
define: a = 1 - 2*hav(D);
define: b = 1 - 2*hav(Hc);
define: L = a/b;
then: hav(2*Z) = ( L^2 ) * hav(2*LHA);
The Azimuth Diagram Example:
D = 40; Hc = 20; LHA = 60;
a = 0.7660; b = 0.9397; L = 0.8152;
hav(2*Z) = 0.8152^2 * hav(2*LHA) = 0.6646 * 0.7500 = 0.4984;
2*Z = ahav(0.4984) = 89 deg 49';
Z = 44 deg 55';
H
On Mon, Nov 24, 2014 at 6:51 PM, Greg Rudzinski <NoReply_Rudzinski@fer3.com> wrote:
Greg L,
The 3x5 format is as follows:
Latitude L
Declination d A B
L +/- d Haversine hv Haversine hv
L +/- d +Haversine hv +P
1- sum Arc Haversine sum
Zenith Distance ZD
LHA hv LHA Canculated Altitude Hc = 90°-ZD
product P = (1-sum * hv LHA)
Greg Rudzinski
