I'm working on it... one of the more interesting problems I've had to deal with recently. I think I may have stumbled onto something analytical...

I'll get what I can and make some drawings later. I know that most of the equations used to calculate the angles (usually for celestial observations) generalize about the radius as though the difference is negligible, but if you modify them to include an "effective radius" in order to increase accuracy, the equations are recursive functions of the angle and some other parameters.

I'll have no problem applying numerical methods, provided I can get to the point where I can begin to apply them! I hope to be finished by the end of the work day, and I may typeset them in PDF format (with diagrams describing my logic) and put them on my webpage. I'll keep you posted.