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Interim Detector Planned at Coude‚ Feed (1Mar93) (from KPNO, NOAO Newsletter No. 33, 1 March 1993) For the past several semesters, the observing schedule at the Coude Feed telescope has been complicated by frequent detector changes as many different CCDs "visit" from other telescopes. Each of our other telescopes has a "resident" detector which is most often used at that telescope (T2KB at the 4-m, T2KA at the 0.9-m, T1KA at the 2.1-m, and S2KA at the Schmidt). At the Coude Feed, the resident detector has been a TI device, most recently TI5, but many observers prefer one of our second generation detectors, which offer better performance. The TI detectors are smaller, less sensitive, and have poorer charge transfer characteristics and cosmetic defects which make them unsuitable for careful radial velocity measurements. Their only advantage has been the small (15 um) pixels needed for higher spectral resolution. While the variety of detectors in use at the Feed has been advantageous for scientific observations, it has meant a lot of extra work for the mountain and instrument support staff. The Coude Feed dewar is scheduled to be upgraded to a Ford CCD with 3072, 15 um pixels eventually, but those detectors have been slow to appear. In the meantime, we will plan to replace TI5 with a smaller Ford device with the same size pixels (15 um), higher sensitivity, better charge transfer, and a modest increase in spectral area (1200 pixels vs. 800). The QE curve for the Ford chip should be a little better than the one given for the new CryoCam detector in this issue, with a QE near 50% at 3500 A and peaking at over 90% at 6000 A. Programs which are awarded time on the Feed in the fall semester will be scheduled with the Ford device (F1KB) unless a compelling reason is given to schedule another chip. When the Ford 3K devices are available, the smaller Ford chip will be replaced. Caty Pilachowski, Todd Boroson
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