NavList:

"Longitude is obviously easy."

Okay, this kind of made my day. Are you familiar with the old old days of usenet, and specifically the group alt.folklore.urban? They used to go "trolling", in the old school sense; not the modern "I'm a bad person on the internet", but rather a nice fishing metaphor: go to alt.math and post absurd proofs of the four-color theorem.

Taking a giant step backward, it sounds very much like you're trying to determine the lat & long of the observer, given the sights taken by a sextant. If you also have a chronometer, then this is in fact the basic problem of celestial navigation, and many people here can tell you how to do this, or even *train* you to do it, for a small fee. If that's not the problem that you're working on, then I guess I'm confused.

In other words: yep, you hooked me pretty good there.