A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2018 Jan 25, 14:00 -0800
For a marine sextant, using an artificial horizon, correct the height measured (Hs) for index error and any arc error at this angle (there's no dip correction needed for an artificial horizon), then divide by two. Correct this new angle for refraction, and Q or P in A if required, to get Ho.
For the Sun or Moon, record a body on body sight initially. Then if you progress to edge on edge, you’ll be able to confirm you’re dealing with semi-diameters correctly if things start going awry. DaveP