NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Fred Hebard
Date: 2019 Jul 14, 21:22 -0400
On Jul 14, 2019, at 15:01, John D. Howard <NoReply_Howard@fer3.com> wrote:Fred,
I do not know a good formula either, but thinking about the geomertry of a telescope's motion will give you some limits.
If your scope is pointing east, but the horizontal axis is tilted one degree left down, your true azimuth is east. As you raise the scope in eleavation without turing the the yoke along the vertical axis the line of sight azimuth will slowly look north of east. At 90 degrees elevation it will point one degree north of your zenith or 89 degrees. The line of sight will not be a great circle. A great circle must go through your zenith and the center of the earth. Your line of sight will go one degree north of your zenith to one degree south of the center of the earth.
The point is that the azimuth at any elevation will not be off more than the tilt of the horizontal axis. This will be true for whatever the zero degree azimuth is. The error will always be in the direction of the lower side of the horizontal axis.
John H. 41N 100W
