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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Francis Upchurch
Date: 2016 Sep 17, 23:44 -0700
We all give a knowing smile when we see the historical film of the captain boldly proclaiming a lat/long fix from a single noon sextant sight. I haven't done that, but close.
A single polarum (nocturnal that just measures angles) shot of Alkaid angle, with "simultaneous sextant alt of Polaris quickly gave me reasonable lat and long.
Latitude.
Ha Polaris 50°42' by sextant
Polarum Alkaid angle gives Q correction -36'. Latitude 50°06 .Spot on.
Longitude.
GHA Aries 78°43'
+SHA Alkaid 153° =GHA Alkaid 231°43' (this would be the polarum angle reading at Greenwich)
Minus LHA alkaid from local Cornwall polarum angle reading 226° = Longitude 05° 43'
Correct long by GPS 5°32', so just 11' out with basic small polarum (I' still working on another "improved version" (more later)
I had only used Kochab before for longitude, but this one shot of Alkaid worked well for both q correction and longitude.
I hope to experiment with my improved polarum soon. this hopefully will give readings to about 6'.
Best wishes
Francis
