--- Robert Clark <bobbygc2001@yahoo.com> wrote: > I've just been informed on the Bautforum.com list in a thread under this same title that I didn't take into account the effects of atmospheric distortion. This limits resolution to .5 arcseconds regardless of the size of the scope if you don't have adaptive optics. Although adaptive optics is the preferred method of dealing with atmospheric distortion if you have a lot of money, there are simpler techniques that can achieve close to the same diffraction-limited results. In particular, a class of video-based imaging techniques called "short exposure imaging" can be used with ordinary telescopes. One of those, amusingly called "lucky imaging" is quite straightforward and has been used to get near-diffraction-limited images of satellites and other objects. Basically, the idea of lucky imaging is that the atmospheric distortions that limit resolution will, every now and then, "flatten out" in front of a telescope for several milliseconds and give a diffraction-limited glimpse of the target. So you take a video of the object, brew a big pot of coffee, and step through the video frame by frame and pick out the best images. There are useful refinements, but that's the idea. See Ron Dantowitz, Sharper Images Through Video. Sky & Telescope, Vol. 96 No. 2, August 1998. Ron Dantowitz, Scott W. Teare, Marek Kozubal. Ground-Based High Resolution Imaging of Mercury. Astronomical Journal, Vol 119 no. 6, June 2000. http://en.wikipedia.org/wiki/Lucky_imaging Another short-exposure technique that requires more computational horsepower than lucky imaging to produce images is speckle imaging: http://en.wikipedia.org/wiki/Speckle_imaging ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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