A two-dimensional photon counting array in operation at Mount Stromlo is described and its performance discussed. The detector consists of a highly intensified Fairchild SL 62925 charge coupled device (CCD) where the spectral response of the system can be varied by the use of intensifiers which have different cathode types (S-20, S-25) as the first electron-emitting surface. The format of the external memory is 760 x 488 event-centered pixels. Prior frame subtraction is used to achieve counting rates of 5 Hz pixel with 3% coincidence correction. The advantages of photon-counting array systems over analog CCD detectors are discussed.