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WIYN Project Summary (1Mar95) (from KPNO, NOAO Newsletter No. 41, 1 March 1995) Since the last Newsletter, activity at the WIYN has centered primarily on commissioning the WIYN telescope itself and its auxiliary facilities. As this Newsletter reaches you, Project attention will have turned primarily to instrument commissioning. The WIYN Observatory continues to have the best delivered image quality (DIQ) on Kitt Peak. DIQ measurements accumulated since 1 September reveal a median image size of 0.7-0.8" FWHM in the R-band for 10s exposures. These exposures are taken under open-loop telescope and Nasmyth instrument rotator tracking. Subsecond images have been seen in longer (10-60s) exposure times but open-loop tracking errors generally degrade image quality for exposure times longer than 10 seconds. Numerous facility-level tasks were completed since the last update, including installation of thermocouples and flat-field lamps on the telescope structure and installation of a dome flat-field screen (i.e., the WIYN "Great White Spot"). Work on the WIYN control system by the University of Wisconsin Controls Group (UWCG) has gradually tapered off during this period as control system delivery has been substantially completed. Major outstanding tasks include completed implementation of closed-loop guiding and completed delivery of documentation and spares. UWCG continues to support "bug" fixes, both major and minor, in hardware and software. However, responsibility for control system maintenance is being slowly transferred from the UWCG to the NOAO/KPNO WIYN operations staff. The Project is currently finishing a series of control system performance and acceptance tests. Completion of these tests have been hampered by a combination of bad weather, closed-loop guiding tests, and the installation of the Wide-Field Corrector. Work on the WIYN control system graphical user interface (GUI) is proceeding smoothly and an alpha version is currently being tested at the telescope. A beta version of the GUI should be released to the telescope operators by 1 February. The most exciting advance at WIYN in recent months was the successful installation of the Wide-Field Corrector (WFC) on the MOS Nasmyth port. The WFC was installed in mid-December under the direction of Dan Blanco, WIYN Project Engineer, after being assembled and tested in the NOAO optics shop. The WFC was designed to produce good, site-limited images over the 1 deg field that MOS/Hydra can position fibers. Initial testing of the WFC in situ with a CCD demonstrated that it could produce at least 0.8" images on axis. The Lockheed Camera was then mounted on the MOS port to allow the acquisition of 14-inch photographic plates. The initial plates were obtained in mid-January and look excellent. While plate analysis is just beginning at this time (late January), the images appear to be sub-arcsecond, circular, and uniform in size over the entire 53 53 arcmin plate field-of-view. These long exposure (20 min) plates were hand-guided. The resulting high quality plates suggest that closed-loop guiding should work quite well. Furthermore, the stellar images across the plate field-of-view show no indication of smearing due to inaccurate field derotation suggesting that the MOS Nasmyth Instrument Rotator (NIR) is functioning well under open-loop derotation. The primary reason for acquiring these plates, however, is to determine empirically the WFC optical distortion pattern. Accurate fiber positioning by MOS/Hydra requires accounting for this pattern in the positioning algorithm. Thus, acquisition of these plates initiates MOS/Hydra commissioning. Given the planned MOS/Hydra commisioning tasks, it seems unlikely at this time (late January) that MOS/Hydra will be available for general shared risk use before 1 June 1995. Work on the WIYN Imager also continues. The heart of the Imager, the STIS 2048 2048 CCD designated S2KB (described in the last Newsletter), is now in regular use at WIYN under Harcon control. The Indiana University Imager group led by Kent Honeycutt has recently upgraded the Filter/Shutter Assembly (FSA) to correct a filter wheel imbalance problem. The initial WIYN Imager filters, a 4 4 inch Harris filter set identical to the other KPNO 4 4 inch Harris filter sets, has been completed and installed. At this time, photometric and flat-field property characterization is about to begin. These parts of the Imager should be completed and commissioned by 1 March 1995. Unfortunately, progress on the Instrument Adaptor Sub-system (IAS), the WIYN guider and acquisition "box," has been slowed in recent months as resources have been diverted to complete the WFC installation and testing. The Project is now working towards completing initial IAS commissioning by early May. This delay in the IAS schedule means that the Imager will not be available for general shared risk use before 15 May 1995. As the advent of science operations nears, assuring a smooth transition from the construction/commissioning team to the operations staff has grown in importance. To facilitate this process, a series of WIYN Workshops has been organized by Dave Sawyer, WIYN Site Manager, who is currently part of the commissioning team but will have overall responsibility for WIYN operations once commissioning is completed. Each Workshop addresses a specific major WIYN sub-system (e.g., the control system, the primary mirror system, the enclosure) and is given by Project members who were involved the construction and commissioning of that sub-system. In turn, Workshop attendees are NOAO/KPNO staff who will be operating and maintaining these sub-systems during WIYN science operations. WIYN is currently being operated every weeknight except NOAO holidays. Continuous night-time operation will be initiated as instrument commissioning warrants but is unlikely to begin before April. Upcoming anticipated major Project milestones include: (1) completion of closed-loop guiding implementation in mid-February; (2) completion of control system commissioning and acceptance testing in early March; (3) MOS/Hydra commissioning completion in late May; (4) IAS/Imager commissioning completion in early June; (5) start of shared risk science operations in late May or early June. Dave Silva
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