A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2021 Apr 6, 07:33 -0700
An ex-meridian by Bygrave is precision overkill . Ex-meridians only need two place precision and can be worked very quickly with a 6 inch pocket slide rule. The best formula is : XM' = .52 (t)(t)(cos Lat)(cos Dec) / (cos Ho). A custom table for .52(t)(t) can be easily made and kept with the pocket slide rule. This cuts the number of slide rule moves to four.