# NavList:

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

**Mathematical Advancement of a celestial COP**

**From:**John Brenneise

**Date:**1998 Oct 23, 3:39 PM

I have some code that takes the place of H.O. 229 or H.O. 249 by numerically solving the following: sin(h1) = cos(phi)cos(beta1)cos(theta-alpha1) + sin(phi)sin(beta1) sin(h2) = cos(phi)cos(beta2)cos(theta-alpha2) + sin(phi)sin(beta2) where h1 is the corrected angle of elevation for a circle centered at latitude beta1, GHA alpha1 and h2 is the corrected angle of elevation for a circle centered at latitude beta2, GHA alpha2. The question concerns running fixes. The COP from the earlier of the two observations must be advanced along the DR course. In terms of the center of the circle, I propose that (beta1,alpha1) must be moved along the loxodrome defined by the course angle for a distance to be scaled by a factor related to the difference between the course angle and the azimuth angle to the celestial object. So, what I need is a good reference and or insight on Spherical Trigonometry to test my assumption. Any ideas? =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-= =-= TO UNSUBSCRIBE, send this message to majordomo{at}roninhouse.com: =-= =-= unsubscribe navigation =-= =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=