Accurate time-resolved optical photospectroscopy with superconducting tunnel junction arrays

Abstract

Superconducting Tunnel Junctions (STJs) have been extensively investigated as photon detectors covering the range from near-infrared to X-ray energies. A 10�2 array of Tantalum/Aluminium junctions has been integrated into the S-Cam3 camera for ground based astronomy. With this camera, the European Space Agency has performed multiple astronomical observations of optical sources using the William Herschel 4.2m telescope at La Palma and the Agency's 1-m Optical Ground Station telescope at Tenerife. Compared to its predecessor, this new instrument features a 10"�2" field-of-view, an optimized IR rejection reducing baseline noise and increasing optical light throughput and ultra-stable operations. In this paper, we review the instrument's architecture and describe the system's performance and in particular the energy resolution and count-rate capabilities of the detector arrays. Finally, we shall present first astronomical images taken during the Optical Ground Station's 2005 and 2006 campaigns which demonstrate the system's timing, photometric and spectroscopic capabilities.