NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bill Ritchie
Date: 2024 Jul 22, 03:43 -0700
Frank, You asked "And what do you find for the actual extreme southern Dec for the entire 18-year period? It's still a few months away, right?". I make the most Southerly at the start of the present period as S28° 43.39' on March 22nd 2006 at 16.54UT. The period ends with a maximum of S28° 41.74' on Oct 9th 2024 at 11.44UT.
You also asked "how many days are there in an average year when the Moon is never visible while the Sun is in the sky, even for a few minutes, for a mid-latitude observer?". Unlike your first question, that is something way beyond inspection of Astron's time almanac page. I will write a python/Skyfield program to investigate this over one, or more, 18 year cycles. Specifying mid-latitude will simplify it a little as the Moon cannot rise twice in the same day at 45N/S. I'll also count as 'visible' any occasions when the upper limb is just risen but is not illuminated. It maybe a while before time allows!
Bill Ritchie
