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WIYN Telescope Update (1Jun94) Rapid progress continues towards the completion of the WIYN construction. At the time of this writing (late April), we are nearing "first light" and the beginning of commissioning activities. Highlights of construction activity between mid-January and mid-April are described below. Much of the activity during this period involved preparation for optics installation and the actual installation of the primary. The primary mirror cell was installed in the telescope and mechanically aligned to center the optical axis of the mirror in the Optic Support Structure and square it to the elevation axis. The primary mirror itself was aluminized at the 4-m coating facility and installed on 8 March. The NOAO WIYN mirror group has tested the active supports for various elevations and reports that the on-telescope hardware is working correctly. The off-telescope portions of the primary mirror thermal control are currently nearing completion and will be ready for early optical tests on stars. Laboratory assembly of the secondary and tertiary mirrors in their cells has been completed and both mirrors have been aluminized at the mountain solar telescope coating facility. At this writing, they are currently being re-assembled in their cells and will be installed on the telescope in the near future. A video rate camera has been mounted at the Nasmyth port to check initial collimation and verify the pointing and tracking of the mount. A science-grade cooled CCD will be substituted for the video camera in early May and image quality measurements will commence. The lenses for the fiber optic fed Multi-object Spectrograph (MOS/Hydra) wide-field corrector are being ground at Rayleigh Optical in Tucson and are expected to be completed early this summer. The corrector cell will be ready at about the same time. Once the corrector is installed on the telescope, the NOAO MOS/Hydra instrument group plans to use a photographic camera to map the field distortion in preparation for spectrograph commissioning. Installation and testing of the telescope control system (TCS) continues as the rest of the telescope hardware is brought on-line. Development of a TCS graphical user interface has started and will continue throughout the commissioning phase. Instrument computers are being acquired for both the MOS/Hydra spectrograph and CCD imager. Telescope completion took precedence over development of the Instrument Adapter/Guider for the WIYN Nasmyth (CCD imager) port during this period. Nevertheless, the general design has been approved and mechanical detailing is underway. Long lead time items such as the guide cameras and integrating CCD for the wavefront sensor have been ordered and some parts of the guider box are currently being fabricated. The guider effort will ramp up following installation of the optics as resources become available. Commissioning of the observatory will begin following final integration and test of the control system. Commissioning activities for both the telescope and instrumentation are expected to continue through the end of the calendar year with science operations starting in early 1995. Matt Johns, Caty Pilachowski, Dave Silva
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