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Robin

That’s the ideal spot for an Owl Perch.  Gnomonic not conformal; I’d forgotten that.  My post you refer to was almost six tears ago when I still had a few grey cells left.  I was just looking for great circles being straight lines.  If it wasn’t for Canopus a Mercator might just about do; the other two stars are quite close to the equator.  I only wanted to know how close to the observatory you’d get. 

Markab (top right) is at 15 18N 108 49’W, so a Mercator might give a reasonable approximation for a Markab, Aldebaran, Sirius fix.  You could do it on graph paper using meridional parts.  Got to make Nories earn its keep.  If Christmass TV gets really bad, maybe I'll try it.  Alternatively, stick with Canopus and look for a suitable Lamberts.

With Sirius apparently due east adding 75degrees ZD as it appears in the photograph on to Sirius’ SSP gives quite a fair attempt at longitude.  Unfortunately, the real Az is 099, the real ZD is about 69 and the extra distance west is only gained by the slope of the LOP.  DaveP