A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Michael Cain
Date: 2019 Dec 11, 13:14 -0800
Frank answered your question re: dip. (And I thank him for the education he gave me with his answer.) As for differences in refraction, in comparing my 2019 and 1993 NAs p A4, there are differences throughout the chart, though the largest I notice at casual glance seems to be .4' (with most appearing to be .1').