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IR Observing Capabilities at NSO/SP (1Sep93) (from NSO, NOAO Newsletter No. 35, 1 September 1993) Several rounds of observing tests have been completed with a HgCdTe IR camera system and the NSO/SP Evans Facility and VTT telescopes. The VTT/Echelle and HSG perform nicely for IR spectroscopy out to the K-band. The IR VTT polarization properties are still being analyzed, but it appears that the VTT-induced cross-talk between linear and circular polarization states is roughly consistent with visible-band measurements. The Evans Littrow spectrograph has proven to be very stable and useful out to wavelengths of 1.8 um (now limited by the focus travel of the Littrow lens). The Evans coronagraph has also been used out into the H-band. Instrumental scattered light currently limits broad-band IR coronal observing, but changes in the baffling may soon allow sky-limited coronal IR imaging. The high QE of the HgCdTe detector (approximately 10 times the QE of silicon CCDs at 10830 A) is encouraging news for several spectroscopic experiments. A 79 l/mm grating borrowed from Kitt Peak (now being installed in the Littrow) may also greatly improve the efficiency of IR coronal spectroscopic studies obtained from the Evans Facility. The NSO/SP IR camera system was funded jointly by Michigan State University, Wyoming Infrared Observatory, and Haverford College. It is available on a shared-risk basis on a limited schedule. Interested observers should contact Jeff Kuhn for further information. Lou Gilliam, Jeff Kuhn, Dick Mann, Matt Penn
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