(Stark4677@XXX.XXX)
Date: Sat Feb 17 2001 - 17:53:47 EST
Sometimes an experiment can help clarify things.
Suppose our dead reckoning puts us about 30° N, 145° W. It's a little before
noon. We get a true altitude of 69° 20'. The sun's declination is 10° N, his
GHA 140°. With this data, using the Ex-meridian tables, we get a latitude of
30° 8' north.
But since we aren't sure of our DR longitude, we work the problem again using
146° west. That gets a latitude of 29° 54'.
Obviously, if we plotted this and drew a line from 30° 8' N, 145W to 29° 54'
N, 146° W we'd have a chord of a circle. The sun's geographic position would
be the center of the circle and his zenith distance the radius.
Bruce
