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CRSP Upgrade Underway (1Sep93) (from KPNO, NOAO Newsletter No. 35, 1 September 1993) With the final Cryogenic Spectrometer (CRSP) observing run of the spring semester completed, we are beginning the upgrade described in the March 1993 Newsletter. The efforts include: 1) modification of the Digital Control Unit to operate with a SPARC host computer; 2) replacement of the 58 x 62 InSb array with a 256 x 256 InSb array; 3) construction of a new triplet camera to provide unvignetted coverage with the larger array. This is a significant undertaking, since the same electronics upgrades will also be made to SQIID and IRIM. We anticipate that the CRSP upgrade will be completed in time for a scheduled engineering run on 18 October, shortly before the first scheduled visitor use on 28 October. A draft version of the operating manual may be available by the latter date, although the performance and operating procedures may still be preliminary at that time. The new camera assembly has the same focal length (53 mm) as the old, so the spectral and spatial resolution per pixel will be increased by a factor of 2.5. The spatial coverage will remain unchanged, being limited by the slit, and the spectral coverage with the high resolution gratings will increase by about 60%. Laboratory tests of the detector give a full well of about 100K electrons, dark current of about 1 e-/s, and single read noise < 30 e- at a bias of 600 mv; operation at larger bias gives significantly increased dark current, but also increased well capacity. We may employ low or high bias modes for low and high background observations, respectively. Observers scheduled for the fall semester should e-mail me for progress reports on the upgrade. It is unlikely that we will turn on the instrument in the lab much before 1 October. Dick Joyce
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