A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Herman Dekker
Date: 2021 Nov 9, 13:06 -0800
I came over this old post from David C and could first not understand what was wrong with the 2 calculated Longitude values.
I asked Starpilot the correct Hc data for the date Time and DR sight and calculated the Longitudes.
I then draw the position line and concluded (as David did) the longitudes are wrong but why?
I used the calculation many times without problems.
Then I realised that the rules learned in the Modern Celestial Navigation Class are not compleet
for this case.
If Longitude >360° subtract 360° If longitude<0° add 360°
I think I need one extra rule.
If calculated Longitude is >180° and <360° then Longitude is 360°-calculated, that is East Longitude.
I wonder if the rule:If longitude<0° add 360° can be replaced with the rule:
If Longitude<0° make value positive en write East Longitude.
See attache Pdf's for Calculation and Plot.
If I am wrong pleace comment.