Infrared camera (IRC) on board ASTRO-F (IRIS): design overview and current status

The design overview and current development status of the Infrared Camera (IRC) onboard the Japanese infrared space mission, ASTRO-F (commonly called as the Infrared Imaging Surveyor, IRIS), are presented. The IRC is one of the focal plane instruments of ASTRO-F and will make imaging and low- resolution spectroscopy observations in the wide spectral range of the near- to mid-infrared of 2 - 26 micrometers . ASTRO-F will be brought into an IRAS-type sun-synchronous polar orbit. The IRC will be operated in the pointing mode, in which the telescope will be pointed at a fixed target position on the sky for about 10 minutes. The pointed observation may be scheduled up to three times per orbit. The IRC has three channels: NIR (2 - 5 micrometers ), MIR-S (5 - 12 micrometers ) and MIR-L (12 - 26 micrometers ). All of the three channels use refractive optics. Each channel has a field-of-view of 10' X 10' with nearly diffraction-limited spatial resolution. The NIR and MIR-S channels simultaneously observe the same field on the sky, while the MIR-L observes the sky about 20' away from the NIR/MIR-S position. State- of-the-art large format array detectors manufactured by Raytheon/IRCoE are employed for the IRC. The NIR channel uses a 512 X 412 InSb array, and 256 X 256 Si:As IBC arrays are used for the MIR channels. Fabrication of the proto-model has been completed and the preliminary performance test is under way.