A 12x10 pixels superconducting tunnel junction array based spectro-photometer for optical astronomy

Superconducting Tunnel Junctions (STJs) have been extensively investigated as photon detectors covering the range from near-infrared to X-ray energies. A 6x6 array of Ta junctions has already been used in an optical spectro-photometer. With this camera, the European Space Agency has performed multiple astronomical observations of optical sources using the William Herschel 4.2 m telescope at La Palma. Following the success of this programe, we are now completing the development of a second generation camera. The goals of this programe were to increase the field of view of the instrument from 4''x4'' to 11''x9'', to optimize IR rejection filters (possibly extending the 'red' response to ∼1 μm), and to increase the electronics readout speed. For these purposes, we have developed a new STJ array consisting of 10x12 Ta/Al devices as well as an improved readout system. In this paper, we review the instrument's architecture and describe the performance of the new detector array