A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Dave Walden
Date: 2016 Jun 18, 05:44 -0700
As Kermit points out, there is parallax in azimuth as well as parallax in altitude when considering the non-spherical earth. As he further says, doing the 3d vector calculation with the non-spherical earth will include this effect. But, there are equations in sources like Chavenant which let you calculate the parallax in azimuth effect without doing the 3D vector calculation. As Kermit says, when looking for exact agreement, it is needed.