The Coded Mask Design and Test Flight Results of A Small Array Germanium Telescope

Abstract

A small germanium array detector had been incorporated into a coded mask telescope and was flown as a piggy-back experiment on the NASA/GRIS high altitude balloon payload. The flight, on the 24th September 1993 from Fort Sumner, New Mexico, successfully demonstrated the use of a compact 3 × 3 germanium array detector to achieve good imaging of X-ray and γ-ray sources. This paper describes the techniques used to select a suitable coded mask pattern for the telescope as well giving a brief overview of flight results. Comparisons are made of the imaging ability of several different classes of coded mask patterns. By applying constraints to the design of the otherwise ’random’ coded mask pattern, the performance in terms of point source resolution is seen to be better than that of masks based on cyclic difference sets and ‘constraint-less’ random masks.