A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2014 Oct 5, 14:17 -0700
Excellent post Frank.
Attached are a few ex-meridian examples by formula vs. standard LOP and then a LAN. Since I know my position exactly by GPS there is good correlation between the ex-meridian and standard LOP reductions. If longitude becomes uncertain then differences will be greater. This can be seen if the formula LHA value is shifted by a few tenths of a degree.
To test the limits of the formula an ex-meridian was done 35 minutes after LAN and has a difference of 1.2' when compared to the standard LOP reduction. So it is best to stay within the limits of Bowditch table 25.