NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunar distance measurement in ideal conditions: attainable accuracy.
From: Alexandre Eremenko
Date: 2013 Jan 6, 23:21 -0500
From: Alexandre Eremenko
Date: 2013 Jan 6, 23:21 -0500
Bill, Thanks for your interesting post. Actually I collect statistics about accuracy of Lunar observations, and you can see my collection in the directory www.math.purdue.edu/~eremenko/Navigation/Accuracy This directory is made for myself, not for the public, so it is not well-ordered, but it is open and anyone can look at it. The best place to start is http://www.math.purdue.edu/~eremenko/Navigation/Accuracy/accuracy.html I know two XIX century publications with significant statistics (many observations). One is by a professional astronomer E. J. White observing from land, another from a professional navigator and a theorist of navigation, F. Bolte, observing from sea checking with a chronometer, and making all precautions to ensure that chronometer error is determined correctly. The same directory also contains my analysis of Cook's observations at Point Venus, Thaiti. In addition I have a lot of my own records. Most of then with my SNO-T, 6x telescope, and a few with Frank's Tamaya with 7 or 8x prismatic. The horizontal axis on all graphs is is in tenths of a minute. And these numbers represent errors in the Lunar DISTANCES, NOT longitudes. The errors in derived longitude are roughly 30 times larger. By the way, I find SNO-T 6x superior to all 7x or 8x prizmatics that I tried. My vision deteriorates with years (as everybody's vision). But it is still OK for long distances, I feel no need in eyeglasses for long distances, and can see Mizar clearly with my naked eyes. (This was an ancient Arab test for vision of those eligible for military service:-) Alex. P.S. Discussions on Lunars accuracy on this list are and were in the past sometimes too heated, so I prefer to avoid them. I think that concrete data speak for themselves. And everyone can make his own conclusion from these data.