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Spectroscopic CCD Availability (1Sep94) (from CTIO, NOAO Newsletter No. 39, 1 September 1994) By the end of the calendar year (more or less), CTIO will have finished converting its most-used spectroscopic CCDs to the Arcon controller. Specifically, the Loral 3K X 1K installation in the Blue Air Schmidt camera is currently underway, and the chip should have been fully tested and commissioned by early December. The Loral 1200 X 800 chip installation on the 1.5-m spectrograph should be completed toward the beginning of first semester 1995. At that time, the only remaining uses of the VEB controllers will be for two little-used detectors, namely the GEC in the Red Air Schmidt Camera and the TI chip (used mainly with the blue long camera on the BME and 4-m echelle). While we recognize that these chips are still superior for certain applications, we feel that the operational burden of keeping both the VEB controllers and the LSI-11 computers functioning for these rather limited uses is not justified, especially because budget limitations have forced us to accept staff reductions on the mountain. We therefore will discontinue offering the TI and GEC detectors, effective first semester 1995 (1 February). We will of course support the GEC chip in the 1.5-m spectrograph until it is replaced by the 1200 X 800 Loral, whether or not this occurs prior to 1 February 1995. As a result, only the Blue Air Schmidt + Loral 3K and the Folded Schmidt + Tek 1K combinations will be available on the 4-m R-C spectrograph. The latter is recommended for use in the red (beyond 7000 Angstrom) as the Loral is expected to fringe badly at this point. If detailed information on the Loral performance is needed to write your proposal for first semester 1995, contact Steve Heathcote or Bob Schommer after 15 September for further information. Final camera/detector assignments for the period will be made at the time of scheduling in late November, when performance should be well-established. We will also take various precautions to enable us to recover from a major failure of the Loral. For most users of the 4-m echelle spectrograph, the best configuration will be the red or blue long cameras + Tek 2K. The Folded Schmidt + Tek 1K may also be useful. A decision on whether to offer the Blue Air Schmidt + Loral on the 4-m echelle will be taken once engineering tests have established whether it offers significant performance advantages over the long cameras. This may not be known until late 1994; again Steve Heathcote and Bob Schommer should be contacted for the latest information. Only the long cameras + Tek 2K will be available on the 1.5-m bench-mounted echelle. The only combination available with Argus will be the Blue Air Schmidt + Loral 3K. Direct imaging work is unaffected, since we are already scheduling only the Arcon-based detectors (Tek 2K, Tek 1K, and Thomson) for these applications. The retired VEB-based combinations will be missed, and it is our intention to eventually replace them with better detectors, run by Arcons. Provisionally, the TI would be replaced by a blue-sensitive Loral 1200 X 800 (or larger if available). This would provide higher resolution than the Tek 2K on the echelle (mainly in the blue), and may also have applications at the 4-m prime focus. We intend to install the best available detector in the Red Air Schmidt. At the present moment this would be our second Tek 1K chip. This would provide a larger format, higher quantum efficiency, and lower read noise than the GEC chip. The replacement work will not be completed during the first half of 1995, and conceivably not until early 1996. We should have a much better idea of schedules and the availability of real (as opposed to virtual) chips early next year, prior to the deadline for second-semester proposals. We recognize that a few users may have to postpone projects for a year, or undertake them with reduced efficiency, but we were increasingly concerned that we could not continue to support the discontinued configurations at an acceptable level of reliability. CTIO Staff
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