Image Orthicon Astronomy at the Dearborn Observatory

Abstract
For a given signal-to-noise ratio, the image orthicon can record stars to a theoretical magnitude limit set primarily by skylight. A “skylight suppression” technique under development appears capable of increasing available integration time and hence the limiting magnitude. Short exposure pictures of the moon under high magnification show about ½-sec resolution with good seeing, and an 18.5-in. (47-cm) telescope; under certain conditions the image orthicon can be used to provide better resolution than possible with emulsions, owing to the shorter exposures which are feasible even with high-magnification projection optics. Among other electronic devices which have been used are the intensifier orthicon, the image isocon, and, most promising, the field mesh orthicon. Brief descriptions of these devices are given as a matter of general interest, although they are not in use at Dearborn Observatory. A list of some Dearborn Observatory projects in electronic astronomy is presented to suggest the wide range of application of this new technique.