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Subject: Re: Need Help w/ Ageton method...
From: William Allen (allen@XXX.XXX)
Date: Mon Mar 03 2003 - 15:57:34 EST
I don't have my Ageton book in front of me (is it Pub 211? or 213?)
because I am traveling, but I think I remember the terminology. This is
my favorite sight reduction method and I use it a lot.
R is the "artificial" arc that is dropped from the celestial body to
intersect as a perpendicular the co-latitude of the observer. Ageton,
like many others, decided to solve the oblique navigational triangle by
dividing it into two right-angled spherical triangles with this
perpendicular. (Others dropped perpendiculars from different points as
well.)
You don't actually need to write down R to solve for intercept or
azimuth, just look it up in the tables from its A value and then
immediately write down its B value. As you probably know, this B value
is a log secant (the A value is a log cosecant) multiplied by 100,000.
The B value for arc R is then added to the A value from declination of
the celestial body. This sum gives you a new A value that you look up
in the tables and right down as K. And the rest just follows the rules
...
Hope this helps.
Regards,
Bill Allen
-----Original Message-----
From: Navigation Mailing List
[mailto:NAVIGATION-L@XXX.XXX] On Behalf Of HGWorks - Phil
Guerra
Sent: Sunday, March 02, 2003 7:18 PM
To: NAVIGATION-L@XXX.XXX
Subject: Need Help w/ Ageton method...
Is anyone willing to help a newbee with the Ageton method? I found a
copy of Ageton's Celestial Navigation, copyrighted 1943. I've gone
through the example in the back chapter on using the method with D.R.,
but I don't understand where he gets the value 'R'. I can see how he
draws the line segment, but where is that value taken from the table, or
is it derived from a formula only?
Thanks
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