In June 1997, NASA made the decision to extend the end of the Hubble Space Telescope (HST) mission from 2005 until 2010. As a result, the age of the instruments on board the HST became a consideration. After careful study, NASA decided to ensure the imaging capabilities of the HST by replacing the Wide Field Planetary Camera 2 with a low-cost facility instrument, the Wide Field Camera 3. This paper provides an overview of the scientific goals and capabilities of the instrument.
We present a design for a near-infrared (0.9 to 5.5 micrometers ) spectrograph for use on any large telescope. For example, the instrument meets all of the scientific and technical objectives requested by the Gemini Telescope Project for their facility infrared spectrograph. The features of the instrument include a wide range of rapidly selectable spectral and spatial resolutions, full-broad-band imaging, integral field spectroscopy, and several cross-dispersed modes. Much of the instrument is based on optical, mechanical, and electronic designs currently in use. The optical design has diffraction-limited performance and no vignetting over a 150" X 150" field of view. The mechanical design draws heavily on our extensive experience with cryogenic mechanisms and uses a cassette system for selection of the large number of possible configurations. The design is very modular and allows a staged implementation of the complete set of potential operational modes.
The Ohio State Infrared Imager/Spectrometer (OSIRIS) is a general purpose near infrared (0.9 to 2.5 micrometers ) instrument that can be used at a wide variety of telescope focal planes. OSIRIS currently uses a 256 X 256 HgCdTe array detector and will accommodate larger arrays when available. OSIRIS has two modes of operation: imaging and spectroscopic. This paper describes the general instrument design and sample scientific results.