NavList:

Robin,

Could you characterize what portion of the issue is coordinate-driven and what portion is geometry-driven? The "sphere" has the same geometry and curvature at every point -- my backyard is just as "curved" as a region near the north pole. But the coordinates on the sphere become singular at the north pole. If I advance a line of position some short distance from the north pole, is the procedure and the result simlar to advancing a line of position at some middle latitude?

By the way, since we do celestial navigation on the celestial sphere, and then pull the coordinates down by the local vertical, should we advance lines of position on the celestial sphere as well? And then does the ellipsoid even matter?

Frank Reed
ReedNavigation.com
Conanicut Island, New England