NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Peter Hakel
Date: 2019 Sep 27, 15:51 -0700
Hi Brad,
Yes, I looked at them; Paul’s results (and underlying models) are much more detailed and I am glad that mine (which are based on Jean Meeus’s book) are good enough for celestial navigation purposes.
In fact, I just received the 2020 Commercial Edition of the Nautical Almanac. Every year at about this time I do spot comparisons between my spreadsheets and this almanac to make sure that the spreadsheets remain accurate enough for the next year. For now, I only peeked at the 2020 autumnal equinox; the almanac lists Sun’s declination on September 22, 2020 as:
N 0° 00.5’ at 13h UT
S 0° 00.5’ at 14h UT
which is consistent with sun.xls placing the Sun on the equator at about mid-hour, so I am feeling optimistic. :-)
The same argument applies to small differences in delta T mentioned by Dave Walden; I use this fit:
https://eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html
Peter Hakel
35° 53’ N
106° 19’ W
