IRIS - AN INFRARED IMAGER AND SPECTROMETER FOR THE ANGLO-AUSTRALIAN TELESCOPE

We describe a versatile infrared camera/spectrograph. IRIS, designed a nd constructed at the Anglo-Australian Observatory for use on the Angl o-Australian Telescope. A variety of optical configurations can be sel ected under remote control to provide several direct image scales and a few low-resolution spectroscopic formats. Two cross-dispersed transm ission echelles are of novel design, as is the use of a modified Bowen -Burch system to provide a fast f/ratio in the widest-field option. Th e drive electronics includes a choice of readout schemes for versatili ty, and continuous display when the array is not taking data. to facil itate field acquisition and focusing. The linearity of the detector ha s been studied in detail. Although outwardly good, slight nonlineariti es prevent removal of fixed-pattern noise from the data without applic ation of a cubic linearising function. Specific control and data-reduc tion software has been written. We describe also a scanning mode devel oped for spectroscopic imaging.