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.

摘要

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 20,000has been developed and extrapolated to specify limiting detectable point-source visual magnitudes for telescope apertures ranging from 7in. to 400in.,and for image-cell angular diameters from 0.5to 60.0sec. 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)