A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2019 Oct 12, 13:22 -0700
Grant Nixon, you wrote:
"The sun travels in an analemma (cf. equation of time) as per below, so a linear approximation would not be great."
Actually, in this case, the analemma and the equation of time are irrelevant. We're only looking at declination. Graph of the declination of the Sun against date during the year. It closely resembles a sine curve, and that's why the circle diagram that I mentioned works as well as it does. The equation of time would enter the picture if we attempted to estimate the Sun's GHA at midnight UT (or any other hour of UT).