NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sun's average declination
From: UNK
Date: 2015 Mar 15, 18:28 -0700
From: UNK
Date: 2015 Mar 15, 18:28 -0700
Looking at the order of magnitude, I am not convinced that the change in the obliquity of the ecliptic is a KEY factor, although it may slightly contribute: 1' in 23 deg versus 12" in 23'. If the effect is real (I believe it is) and not just some noise in my computation, I suspect the motion of perihelion w.r.t. equinox to be the main culprit. I tried to approximate the average over a tropical year by integrating over 365.25 days (365.2425 would be more correct, but more work).
Herbert Prinz
