A 12×10 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 6×6 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”×4” to 11”×9”, 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 10×12 Ta/Al devices as well as an improved readout system. In this paper, we review the instrumentʹs architecture and describe the performance of the new detector array.