A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2017 Jul 21, 10:24 -0700
See attached graph showing minutes behind and ahead of mean Sun through the year. This variation from the mean is caused by the Earth's elliptical orbit and axis tilt.
Picking the moment of LAN for longitude determination will not be as accurate as equal altitudes because the Sun hangs for about 4 minutes at the maximum altitude. Each minute of time off will result in 15' of longitude error.