Development of superconducting tunnel junction arrays for astronomical observations

The original S-CAM1 and 2 systems were a first successful demonstration of a camera for optical astronomy based on superconducting sensors. However, a number of shortcomings were identified during the observing campaigns at the William Herschel Telescope at La Palma that triggered this work. As the plate-scale was chosen to slightly over-sample the telescope’s point-spread function under ideal seeing conditions, the average atmospheric conditions at the WHT combined with the limited field-of-view of the early 6×6 array severely limited accurate photometry. Also, the quality of the sensor and the IR background limited the spectral resolution of the instrument. This work was therefore focussed on the further understanding of the fundamental physical limitations of these superconducting tunnel junction sensors, the fabrication and optimization of medium sized arrays and the substantial improvement, implementation, verification, calibration and exploitation of a camera system, called S-CAM3.