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Re: Need Help w/ Ageton method...
From: William Allen
Date: 2003 Mar 3, 12:57 -0800
Message
From: William Allen
Date: 2003 Mar 3, 12:57 -0800
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@LISTSERV.WEBKAHUNA.COM] On Behalf Of HGWorks - Phil Guerra
Sent: Sunday, March 02, 2003 7:18 PM
To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
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
