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Special Opportunity for High Spatial Resolution...(1Mar95) IR Imaging Programs (from KPNO, NOAO Newsletter No. 41, 1 March 1995) We will conduct a special observing program during the fall 1995 and spring 1996 semesters using COB/DLIRIM on the 4-m telescope for high resolution imaging at 3.3-4.1 um. Observations will be obtained by KPNO staff in a service observing, queue-scheduled mode, in such a manner as to obtain as much data as possible for all approved programs. To provide an opportunity to see this unique capability in action, visiting observers will be welcome to participate during the observing sessions. However, these may not be totally dedicated to a visitor's particular program under these rules. The DLIRIM configuration provides 0.1"/pixel and a 25" field of view. It critically samples the Airy disc in the L and L' bands (3.3-4.1 um) and slightly undersamples at K. In an experiment conducted last fall, high speed data acquisition followed by shift and add postprocessing gave images at L' with diffraction limited cores and highly uniform PSF over this field. Due to the high thermal background of the sky longward of 3 æm, very short integrations remain background limited. There is no loss of sensitivity in this mode at these wavelengths. This experiment was reported in the December 1994 NOAO Newsletter. A large part of the spatial resolution advantage is retained at K in the high speed mode, but the data are no longer background limited, so a severe penalty is paid in sensitivity. The PSF is also more sensitive to atmospheric conditions and more likely to vary across the field of view. For these reasons we are emphasizing programs at 3.3-4.1 æm in this opportunity. For other programs, the 2.1-m telescope offers larger field (50") while retaining some advantage of higher resolution (0.2"/pixels, 0.6"-0.8" FWHM images at K). If you are interested in proposing for observations with COB/DLIRIM on the 4-m telescope, please submit the standard KPNO proposal form. COB/DLIRIM proposals will be reviewed by the TAC as part of this special observing opportunity. Note that the longer term plan for the instrument calls for its permanent relocation to CTIO, nominally in fall 1996, so this is an opportunity of limited duration. Please contact rprobst@noao.edu for details on modes of use, sensitivity, etc., of COB/DLIRIM prior to proposing. Ron Probst, Caty Pilachowski
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