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6 December 1999 Operating the ISO-SWS InSb detectors at temperatures above 4 K
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Abstract
The Short-Wavelength Spectrometer (SWS) is one of the four focal plane instruments of ESA's Infrared Space Observatory (ISO). The satellite was launched on November 15, 1995 with a super fluid Helium content of about 2300 liters to keep the telescope, the scientific payload and the optical baffles at operating temperatures between 2 and 8 K. On April 8, 1998 the liquid Helium depleted and the instruments were switched-off when the focal plane reached a temperature of 4.2 K. A satellite engineering test program was conducted between April 20 and May 10. Timeslots before and during the test program were used to operate the InSb detectors of the SWS instrument while the temperature of the focal plane slowly increased up to 40 K. The instrument was used to record spectra of 260 stars between 2.36 and 4.05 microns at a resolution of 2000 and with high S/N. Goal of the program was to observe a set of stars covering the entire MK spectral classification scheme to extend this classification scheme to the infrared. We discuss changes in the instrument relevant for operating and calibrating the instrument at temperatures above 4K: changes in the InSb detector behavior (dark levels, noise, response, ...), behavior of the JFETs and geometry changes in the grating scanner mechanism. We also show that the calibration of the data obtained after Helium loss is accurate, resulting in a data set of great scientific value.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bart K.P. Vandenbussche, Mattheus WM de Graauw, Douwe A. Beintema, Helmut Feuchtgruber, A. Heras, D. Kester, F. Lahuis, R. Lorente, K. Leech, E. Huygen, P. Morris, Peter R. Roelfsema, A. Salama, Rens Waters, and E. Wieprecht "Operating the ISO-SWS InSb detectors at temperatures above 4 K", Proc. SPIE 3759, Infrared Spaceborne Remote Sensing VII, (6 December 1999); https://doi.org/10.1117/12.372695
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