NavList:

I've had a couple more thoughts on this puzzle. First, I tried the image analysis again and got results with more scatter than expected, so I think the "error bars" on the position that I gave previously should be doubled.

Also, the estimated error in UT has a rather different interpretation than in traditional celestial navigation since few sailing ships travelled at 18,000mph.

I've also been wondering about the cities faintly visible below the horizon. How could we ever identify them given that there is clearly cloud cover across much of the land below? Well, I spent this evening puzzling over it. At first I used various "flat images" of city lights seen from orbit. From that I had a good guess that the triangle of small cities near the center of the image were probably Grand Island, Nebraska plus two neighbors (Hastings and Kearney). Then while googling around, I discovered that Google Earth has a city lights layer built in, so I was able to align things just right and sure enough, it all checks out. Off in the distance below iota Ceti, those fuzzy blobs of light are the lights of Denver, Colorado and nearby cities showing through overcast. A comparison image is attached. The top half is a contrast-enhanced copy of the original astronaut photo. The bottom half is a screenshot from Google Earth.

So now we can do this as a dead reckoning problem, as well as a celestial navigation problem. :)

-FER

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