CTIO and The Ohio State University are upgrading the Ohio State Infrared Imager and Spectrometer (OSIRIS) with a 1024 format HgCdTe array. It will be made available as a facility instrument for Semester 1999B.
The science grade array from Rockwell is now (January 1999) in the instrument and being tested in preparation for scheduled engineering runs in February and March. Look for information regarding OSIRIS performance on the CTIO infrared instruments web pages in March. Observers with scheduled time at CTIO in 1999A with the IRS or CIRIM will be given the opportunity to observe with OSIRIS where appropriate. We expect that OSIRIS will be the instrument of choice for IR imaging and spectroscopy for 1999B and subsequent semesters.
A brief summary of OSIRIS capabilities follows. Please see the September 1998 NOAO Newsletter (No. 55) for more details. OSIRIS provides two imaging scales. On the 4-m, this will maximize efficiency with the f/14 tip-tilt system under differing conditions. A 0.15" pixel scale will take advantage of Cerro Tololo's best corrected seeing, while a 0.4" pixel scale will allow productive observations even when the site seeing is not at its best. The square field of view will be approximately 70" on a side at the fine scale on the 4-m; the field of view at the coarser scale will be about 3.5 × 3.5'. The corresponding fields on the 1.5-m will be 2.7' × 2.7' at 0.4" pixel and 10.3' at 1.1"/pix. The filter set includes JHK and narrowband filters.
In addition to 1-2.5 µm imaging, OSIRIS provides spectroscopic capability in the same dewar. The new pixel scale will result in resolution 2900 spectroscopy covering each of the J, H, or K bands in one grating setting. This mode uses the fine pixel scale and the slit will be approximately 3 pixels wide (0.45" on the 4-m). In addition, a cross dispersed mode will cover J, H, and K bands simultaneously at resolution 1200. The XD mode will use the 0.4"/pix scale with a slit about 1.2" wide. The IRS spectrometer will remain available for IR spectroscopy at higher resolution and/or wavelengths longer than the K band.
If you have questions regarding OSIRIS, please contact Bob Blum, Patrice Bouchet, Brooke Gregory, or Ron Probst at CTIO (rblum@noao.edu, pbouchet@noao. edu, bgregory@noao.edu, rprobst@noao.edu).
Bob Blum (rblum@noao.edu)