The Limits of Detectability of a Low-Light-Level Point-Source Sensor as a Function of Telescope Aperture, Sensor Resolution, Night-Sky Background, and Pre-readout Electron Gain.
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
Pagination or Media Count:
Based on laboratory measurements and on field experience in detecting G-type stars and point-objects by reflected sunlight, a figure of performance of a low-light-level sensor operating continuously at standard TV rates and incorporating a variable pre-readout current gain of 20,000 has been developed and extrapolated to specify limiting detectable point-source visual magnitudes for telescope apertures ranging from 7 in. to 400 in., and for image-cell angular diameters from 0.5 to 60.0 sec. The detection criterion, expressed in video SNR, is that the point-source images in typical real-sky situations be detectable on the screen of a video monitor with essentially 100 probability of detection by a human observer. After three limiting cases are discussed, camera-tube saturation is considered. Levels are determined for the present sensor and for sensors of the future. Modified author abstract