"Test Facilities, Equipment and Methods." . . "Solar flares." . . "HIGH ALTITUDE OBSERVATORY BOULDER CO." . . "Astrophysics." . . "Operation." . . "Densitometers." . . "Performance(engineering)" . . "Circuits." . . . . . "The High Altitude Observatory Isophotal Contour Densitometer"@en . . . . . . . . . . . . . "For many years the High Altitude Observatory has engaged in a program of observations of the spectacular motions of giant solar prominences rendered visible in monochromatic light by the Climax coronagraph. Motion picture studies of these films and similar ones taken at other observatories have revealed the extraordinary nature of the force fields involved, and have pointed to the need for further quantitative work, particularly that involving the measurement of the growth of luminous areas in prominences as a function of time. Because of the limitations for this work of other contouring methods the staff of the High Altitude Observatory has sought to develop a new type photometer capable of analyzing films from motion picture sequences fast enough for the problem at hand. The isophotal contour densitometer described in the report is a first breadboard model of an instrument of this type."@en . . . . "Solar disturbances." . . "Photointerpretation." . . "Modification kits." . .