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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Antoine Couëtte
Date: 2021 Oct 24, 08:04 -0700
In reply to this second post, from N41°18.4' W072°04.6' and from my previous picture, I am measuring the Moon Upper Limb height at 82mm above the sea horizon, i.e. at 0°29.7': above the horizon :
Then I am getting UT = 21h57m31s for Upper Limb at 29.7' above the Horizon, with Azimuth equal to 085.2°, quite close from the corrected 85° announced yesterday .
For this same UT time, I am getting Lower Limb at 0°04.1' above the Horizon, which makes a "contracted" apparent vertical Diameter of 25.6' vs. 30.1' for a horizontal "lateral diameter", which seems realistic. Hence the actual lower limb should be visible then, were there not these houses ... seems reasonabe/consistent with picture lateral Diameter equal to 83 mm and UL at 82 mm from Sea Horizon.
How accurate time wise ? Low Alt refraction may be subject to significant variations. Let's assume it to be under 4' ... then our time measurement should accurate to about +/- 1 minute of time. Probably better since the LL seems to be fully consistent with UL position as indicated just here-above. So I would venture into saying that this UT determination is accurate to +/- 20 seconds of UT time.
Antoine M. "Kermit" Couëtte