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As dome seeing is reduced by interior flushing and careful removal of heat sources, the full realization of superb seeing afforded to some astronomical observatory sites becomes dependent upon telescope optical alignment. This paper describes a simple, inexpensive way to determine the sources of image degradation due to optical misalignment and gives examples of telescopes which have had specific aberrations identified and corrected. Wavefront curvature sensing is employed together with any focal plane CCD camera available to the observer. Several stored through (but not at)-focus images, requiring only a few minutes of precious observing time are all that is required to characterize the optics under test. Further, more ambitious testing is outlined for which primary mirror support, structural flexure, or temperature induced problems may be uncovered. Finally, a method of aberration correction using an optical phase plate is demonstrated for two telescopes.
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