NavList:

Given two sights we get a two point fix which we resolve by what is close to where we think we are.

Two equal sights without knowing the altitude can not yield a point solution. Greg's answer maybe possible but they do not constitute the complete solution.

As both I and Peter Hakel pointed out, the position loci is an arc, part of a great circle. It is a great circle passing through the midpoints of the P->C arcs and perpendicular to the great circle through the two stars.

See attached illustration to follow this reasoning.

The great circle containing the stars defines an axis of symmetry which passes through the second great circle that contains the solution loci. Where that axis intersects the position GC is 90° from each star. Move 1° on the position loci GC closer to the stars from the 90° point and the arc between those points defines altitudes greater than 1°.

The attached illustration further shows how the Sun 6° or more below horizon restricts the position loci.

We are left with the sawtooth labeled part of the arc as a possible position.
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------