NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Matus Tejiscak
Date: 2025 Mar 8, 13:33 -0800
Oh, clever. I took a portion of the penumbra that I found suitable for this (see the red rectangle), aligned the edge of the shadow horizontally and took the median of the luminance of every row of pixels, gamma-decompressed it, and plotted it as a function of the y coordinate. From the plot, the transition takes about 28 pixels. Since from the POV of the body that casts the shadow, the penumbra has always the same size as the diameter of the light source, this gives us about 33' per 28 pixels. Since the feet of the shadow spacecraft are some 650 px apart, which we assume to be 3.5m, this yields a distance of 15-16 m, depending on where exactly you decide to put the endpoints of your measuring tool in Gimp. :)
I'd say that's a fairly good match with the previous approaches, all things considered.
What did you get?
Matus
