NavList:

Frank.  I follow what you’re saying as far as ‘Your thumb is pointing right at the north celestial pole’.  However, if navigating at night, I want a north reference on my horizon.  Assuming for the moment that Polaris lies exactly at the North Celestial Pole, if I fly towards Polaris and do a heading check, my true heading will be 360 degrees.  If I drop my eyes to cross my horizon perpendicularly and note that exact point and then forget Polaris and fly towards it, my heading will still be 360 degrees.  I will be flying north along my meridian (a great circle). 

The last time I saw Orion was looking out of my south facing bedroom window 53.10N 000.32W at about 22.00 on 31^st January 2017 when Orion was bearing about 190 degrees.  Therefore, using the ‘pistol’ method described, my thumb would have been pointing at Polaris about 37 degrees behind my head.  That’s fine, but what would happen if I did successfully follow the great circle along the Orion Arrow (less 8 degrees) and though Polaris.  Would that great circle drop down to cross my northerly horizon perpendicularly?  Maybe it would. The axis of the Orion Arrow (less 8 degrees) lays NS so it’s on a meridian.  Maybe it’s the same great circle that comes down from Polaris to my northerly horizon.  In that case it would work.

However, looking over my shoulder to find my northerly horizon isn’t very practical, but if the great circle crosses my northerly horizon at 360 degrees, it must also cross my southerly horizon at 180 degrees so the method is practical for field navigation.  DaveP