NavList:

Hello, David!

The exact year here is not important, because I don’t expect an accuracy of level of minutes of arc. Error of 1 year, 2 years, 20 years — it doesn’t matter. Equatorial coordinates of Stars do not change so significantly over these periods of time.

I don’t think there are 4 possible longitudes.

We don’t even need two star maps to identify the location. One is enough. The other servs for recheck.       

If these maps were positioned as top views (horizon represented as circle and the center point as zenith), it would be easy to get geographic coordinates of location only from one point in the map: from zenith. The equatorial coordinats of the zenith (using for example Stellarium) with little calculations gives us the location. Declination of the zenith is equal to latitude. Right ascension (converted to SHA) and GHA Aries on date and time allows to get longitude easilly.  

But in this case the maps are dissorted. But if the elliptic line in the star maps represents the horizon, then any 3 stars near the horizon can be used to get the position fix. Besides not only navigation stars can be used. If the equatorial coordinats of stars are known the rest is traditional navigational problem.

PS: I find your “lateral thinking” more interesting than my trivial calculations. Your approach is more thinking "out of box". And that's great!  

Modris Fersters