A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2018 Dec 25, 09:46 -0800
I'm back to the "same-name vs contrary-name" topic for the All-Haversine SR.
The ZD formula works well if Lat and Dec are entered as signed values according to the "N|E positive; S|W negative; ZD positive if shadow points North" rule.
However the Azimuth formula requires to ignore the Lat sign and to follow the "same|contrary" rule when the PD (polar distance) is calculated.
What if the PD definition would be amended as follows:
the elevated Pole distance: ePD = (elevated Pole's latitude) - Dec
For an observer in Southern Hemisphere this would mean: ePD = -90° - Dec which is always correct if Dec is signed. The same is true for the observer in Northen Hemisphere: ePD = 90° - Dec.
I'm not sure if it does more harm than clarifies/unifies the calculation process...