A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Sean C
Date: 2020 Dec 25, 00:45 -0800
"So what's up with the bump around the Arctic and Antarctic Circles? I'm not sure why those are the local maxima, but I suspect it's dependent on refraction at the horizon."
Funny you mention that. In my previous post, I wrote that "Interesting things start happening at 67°33' (N or S)." However, in 2018 the Arctic and Antarctic Circles were at 66°33'. It only took me a few moments to realize that my spreadsheet is taking refraction into account and using the "standard definition" of rise/set being the moment the apparent center is 0°50' below the horizon. [At least I think that's the main reason for the discrepancy.]
Interesting. I'm going to do some investigating.