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Index correction, was: Got your book, Bruce Stark
From: Alexandre Eremenko
Date: 2004 Nov 19, 11:07 -0500
From: Alexandre Eremenko
Date: 2004 Nov 19, 11:07 -0500
I was also puzzled with this: On Fri, 19 Nov 2004, Jim Thompson wrote: > "I get wildly > variable notions of index error from a horizon or a star. I wear trifocals, > and my eyes were never particularly sharp...". Fits my experience, which is > reassuring. I've been finding the sun more useful, and you confirm that > too. I don't wear eyeglasses for long distances (need them for reading only) and by all tests, my long-distance sight is perfect. A priori I would expect stars measurements to be more precise than Sun measurements. But my practice shows that it is exactly opposite. Sun is better for the index correction. And my attempts to determine the "instrumental correction" (due to the non-uniformity of the arc) from star-to-star distances fail so far. Why is this so? Does our "day vision" have higher resolution than the "night vision"? Alex.
