A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2023 Nov 6, 07:24 -0800
Wow, Antoine. Thanks! That all looks very convincing, though I admit I haven't reviewed any of your numbers in detail yet. I will do so soon! :) I'll have to look at my "quickie" analysis again, too, which yielded a somewhat different time.
By the way, for mid-northern observers, try the Alnair challenge during the next few weeks. This is the time of year when Alnair crosses the meridian within one or two hours after sunset. But you need a clear southern horizon if your latitude is close to the co-dec of the star. From my location in southern New England, Alnair's apparent meridian altitude is only about two degrees. Of course if I board my yacht tomorrow at 9:00am and instruct the captain to sail south 60 nautical miles, then Alnair's corrected altitude will be a degree higher at meridian passage which would happen tomorrow around 19:03 LMT (near enough to 7pm zone time in most locations). And to reiterate from my first post, it's easy to identify Alnair based on the faint stars in pairs that make the "neck" of Grus.
Today's TO-DO list: get yacht, hire captin.