This announcement affects all DIS users for the remainder of this scheduling quarter and quite possibly extending into 3Q2002. Please read carefully. Due to an unfortunate engineering accident, the blue side of DIS will be inoperable for an indeterminate length of time, possibly as short as a month but perhaps up to three months or more. During reassembly of the blue DIS camera, following installation of a new field flattening lens and other modifications, an attempt to dislodge a small piece of foreign matter on the CCD surface resulted in damage to several of the hair-like "bond" wires on the chip. We have sent the CCD back to EEV/Marconi for evaluation; if it can be repaired, the detector could be returned to service in approximately 4 or 5 weeks. However, it is quite possible that the CCD is irreparably damaged. To ensure that we can recover use of the blue side of DIS asap, we have placed a rush order with EEV/Marconi for a replacement detector. A new CCD typically takes about 14 weeks to manufacture, test, and install. We know of no other existing identical detector that could be obtained on a faster time scale. Also, it is not possible to reinstall the old DIS blue camera at this time because of the modifications made during the recent DIS upgrade. We believe that the red side of DIS is operable, even without the blue side, but the testing of this will not be completed until later today. Assuming that DIS will be usable in red-side-only mode, users for all scheduled DIS programs should consider the following options: 1) Use DIS as is, red side only, 2) Use another instrument for your scheduled science program, 3) Notify your TAC that you wish to have your time reallocated to another science program, or 4) If institutional TACs cannot use any time returned to them, it should be declared OPEN asap. For programs scheduled in May that use DIS (there are no scheduled DIS programs remaining in April), please must notify your institutional scheduler and me by e-mail by Friday 3 May with your intentions, regardless of which option you choose. For programs whose time is to be reallocated, the institutional schedulers should notify me of the program changes as soon as possible. A call for modifications to scheduled DIS programs in June will be deferred until we have an assessment of the chances and schedule for repairing the damaged CCD. In addition to being posted to apo35-general, this message is being sent to institutional schedulers and User Cmte members; please make sure that it is appropriately distributed to affected users at your institution. DIS is and long has been our most heavily used instrument by a substantial factor and, with the recent electronics and detector upgrade, is in effect our newest and most modern instrument. Every effort is being made to return its full functionality at the earliest possible date. Fortunately, a glance through the observing programs suggests to me that it will be possible to carry out many of them using the red side only. If there are any comments or questions, please direct them to me. Ed Turner APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 570 in the apo35-general archive. You can find APO the archive on http://www.astro.princeton.edu/APO/apo35-general/INDEX.html APO To join/leave the list, send mail to apo35-request@astro.princeton.edu APO To post a message, mail it to apo35-general@astro.princeton.edu APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO