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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Kent Nordström
Date: 2009 Mar 1, 11:53 +0100
Referring to [7465] from Frank Reed, [7471] from Wolgang
Köberer and [7477] from George Huxtable. Thanks for providing your views on the
possible limitations in distance when using the Dunthorne formula. And thanks to
Wolgang, who translated the text from the German manual much better than I did.
I am not aware what Wolgang will do ref to Georges question so I provide
the formulas without any intention to interfer in Wolgangs
effort.
The
formula no.18 in the German manual, page
386:
Quote
cos
D = cos Δ + cos m * cos s
* ( cos D cos Δ
)
cos m * cos s
(Formel von
Dunthorne)
Un-quote
In
the above formula:
D =
true distance
Δ =
H h, true values of altitudes
m,
s = H, h
m, s
= H, h, apparent values of altitudes
D =
apparent distance
Δ = H
h, apparent values
These
designations have been taken from another issue of the German manual, I dont
know which because I just have copies of some pages from these
manuals.
The
formula no.20
Quote
cos
D = cos Δ - 2 * cos m * cos
s * sin ½ ( D + Δ ) * sin ½ (
cos D Δ
)
cos
m * cos s
Un-quote
That
is, the formula no.20 is the same as no.18 but put into another
form.
Kent
N
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