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Re: SNO-T tests
From: Alexandre Eremenko
Date: 2005 Dec 10, 12:04 -0500
From: Alexandre Eremenko
Date: 2005 Dec 10, 12:04 -0500
Dear Frank, > No, I haven't yet. Tell us the results when you do. > I think the method works despite the parallax issue. > The only assumption is > that the measured angles should be increasing linearly. It is exactly this assumption I had doubt about. > The fact that the > pattern repeats with a one degree period over two full > degrees of measurement > gives me some confidence that this technique > is measuring something involving > micrometer error. What else could produce such cyclic behavior? That's a strong argument. I will be totally convinced when you measure another sextant which will not show the sinusoid pattern. I made a try yesterday, but instead of the expected sinusoid pattern I obtain something which looks more like "white noise". The interval between the lines was 2.3' and I made one full turn. The distance was approx 16 feet, and the mean quadratic deviation of the measurements was 0.17'. But there was nothing resembling a sinusoid pattern. > Looking at all those lines and their reflected images through the sextant > drove me nuts so I switched to the "one line above - one line below" I found the most convenient pattern 1 line above and 10 below and I have three pictures, 30 lines total. But it is definitely important that that "one line" is in exactly the same position on all pictures. Alex.