Project Echo: Boresight Cameras

The conventional method of evaluating the tracking performance of radar antennas has been to provide a camera-lens system mounted on the antenna structure to provide an optical line-of-sight parallel to the radar beam. This permits the recording on motion picture film of the radar pointing error, whenever the object being tracked is capable of being photographed. Camera instrumentation of this type was provided for both Holmdel antennas, the (iO-foot paraboloid transmitter and the 20-foot horn receiver.* The brightness of the Echo satellite was expected to be greater than that of a first-magnitude star. Experience in astronomical photography indicated that first-magnitude stars could be recorded 011 Tri-X negative film (Eastman Kodak No. 7233) with an exposure of -JV second and a lens aperture of f3.5. Accordingly, it was decided to use a camera speed of four frames per second. This frame rate provides an exposure time of ^ second and at the same time affords 16 minutes of continuous camera * Although this equipment was designed by the Bell System as part of its research and development program, it was operated in connection with Project Echo under Contract NASW-110 for the National Aeronautics and Space Administration. 1227