NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Lance Cowled
Date: 2022 Aug 8, 20:35 -0700
Many thanks for your very detailed response. There is much I can learn from this. The 4th 'sighting' doesn't have any typos that I can see. Anti Spoof Pro gave Hs as 43°07.4'. I checked it carefully when I wrote it down but I can't go back and check it with ASP as it provides real time data only. I have to admit that I rounded to the first decimal point of the minutes in DR position in my post, though. ASP was actually reading 42° 49.37'S 147° 15.73'E as my GPS location. Although it's a tiny difference, it gives Hc of Hc 43°57.9' on the USNO web app clone on this web site. If I use the GPS position with minutes rounded to a single decimal point, I get Hc = 43° 57.8' for Hc from the USNO Web app clone. My copy of the 2022 Nautical Almanac gives the moons HP as 56.0 at 0500 and 0600 UTC, which gives a total correction of 55.1', which agrees with the USNO web app clone and gives Ho=43°58.5'. The difference of 0.6' is a bit larger than I expected, so thank you for alerting me to the limitations of the tabular corrections in the almanac. It's close enough for oceanic navigation, of course.