IRC: An infrared camera onboard the IRIS

Basic design and current development status of IRC: an infrared camera onboard the IRIS (Infrared Imaging Surveyor) is presented. IRC is one of the focal-plane instruments of the 70cm cooled telescope of the IRIS. IRC utilizes recently developed large-format IR arrays for imaging and low-resolution (resolving power approximate to 50) spectroscopy at wavelength 1.8 similar to 26 mu m IRC consists of 3 camera channels: NIR (1.8 similar to 5 mu m), MIR-S (5 similar to 12 mu m), and MLR-L (10 similar to 26 mu m). These 3 channels simultaneously observe different fields (10'x10' FOV each) of the sky, with diffraction-limited spatial resolution. One critical component limiting the performance of the IRC is the performance of large-format arrays: 512x412 format InSb (NIR) and 256x256 format Si:As IBC (MIR-S, MIR-L) arrays operating at very low temperature (<15K). Performance test of the Si:As array manufactured by the Hughes/SBRC is under way, and the preliminary results is presented. Design of the camera optics and the optical components is also presented. IRC is operated under the pointing observation of about 500 sec exposure time, and the development goal is to achieve high point-source detectivity limited nearly by the confusion due to faint astronomical sources.