"Spatial distribution." . . "Stars." . . "Angles." . . "Atmospheric motion." . . . . . . . . . "Preliminary Experimental Measurement of Isoplanatic Angle"@en . . . . . . . . "Group 67 has designed and built an isoplanometer, an instrument which remotely measures the isoplanatic angle associated with atmospheric turbulence conditions. The isoplanatic angle is loosely defined as the angular field over which the spatial transfer function of the atmosphere can be assumed to be invariant. Verification of the instrument required nighttime testing using stellar sources to measure current atmospheric conditions. Preliminary results from a verification experiment and a brief description of the instrument are presented. Full instrument verification requires locating the instrument at a better astronomical site; therefore, our data should not be considered a valid characterization of the atmospheric conditions in Lexington, Mass."@en . . . . . . . . . "Measuring instruments." . . "Sources." . . "Night." . . "Sites." . . "Astronomy." . . "Instrumentation." . . "Meteorology." . . "Turbulence." . . "Measurement." . . "Transfer functions." . . "Test facilities, equipment and meteors." . . "MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB." . . . . "Test and evaluation." . .