Prospects for γ -ray Imaging Telescopes

Possibilities concerning the identification of sources of gamma-radiation with known astronomical objects are considered. The angular resolution of the COS-B telescope is typically + or - 5 deg for 100 MeV photons. But more precise estimates of the most likely location of gamma-ray sources have been made by applying image processing techniques. Nevertheless, the best error boxes include approximately 1000 stars having a magnitude m less than 15 and a much higher angular resolution is, therefore, required to make a unique identification possible. The value of applying coded aperture techniques in a high angular resolution telescope for X-ray astronomy has been demonstrated by Proctor et al. (1978). A practical telescope for astronomy at high energies has been described by Carter et al. (1980). At low energies, an imaging telescope could be constructed by making use of position-sensitive detectors initially developed for use in medical physics. By making use of the considered approaches, it appears feasible to raise the techniques of gamma-ray astronomy to a level comparable with those that exist at other wavelengths.