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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: HO 211 with Sadler method
From: Stan K
Date: 2016 Jul 27, 14:04 -0400
Greg,

You said "Why Ageton didn't apply his A & B log values to the standard spherical law of cosines formulae is a mystery."

Yes, that succinctly states what I have been trying to ask in recent messages.

Stan

-----Original Message-----
To: slk1000 <slk1000@aol.com>
Sent: Wed, Jul 27, 2016 11:52 am
Subject: [NavList] Re: HO 211 with Sadler method

John,
" To do the law of cosine formula one would need to look up the log sin of Lat. and Dec. then add them then go to another table to get the sine of that sum.  Then go to another table to get the log cosine of Lat., Dec., and T, add them up then go to another table to get the cosine of that sum etc. etc. etc.  No one, that I could find, printed a table of sin, log sine log cosine, and cosine on one line for every minute of every degree.  So easy to use but no one seemes to have printed one."
The first appearance  of the sin,log sin,log cos,cos arrangement is in Hewitt Schlereth's first book COMMON SENSE CELESTIAL NAVIGATION  published in 1975. His tables saved reduction time but still had those nasty 9.xxxxx log values. The Ageton secant cosecant  x 100,000 log values eliminates the 9.xxxxx nasties. Why Ageton didn't apply his A & B log values to the standard spherical law of cosines formulae is a mystery. The Ageton Classic table combines Ageton's A&B log values with Schlereth's trig format for an improved retro modern short sight reduction table that can use any position as an assumed position (very convenient). I will have to give the late Hanno Ix (bless him) a hat tip for inspiring the use of log secants log cosecants in place of log cos and log sin for various CN applications.
Greg Rudzinski
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