NavList:

David,

I agree with John that the angle between the stars would be the same everywhere on Earth, and worse than that, we know it already.

Your suggestion is that we measure the two altitudes, then measure the angle between the stars, and by basic spherical trig (like a lunar) we can calculate the exact difference in azimuth between the two bodies. Agreed. But we could also calculate the true angle between the stars from almanac data --without observing the angle between the stars-- and then using the corrected observed altitudes we could calculate the exact difference in azimuth between the two bodies. Right? This implies that the observation cannot add anything navigationally useful. The information is already present in the known Dec and GHA of the two bodies.

I will say this though: you had me for a while, and I still don't see why it doesn't work in terms of the additional circle of position that you described. 

Frank Reed