GRIS - THE GRATING INFRARED SPECTROMETER

The grating infrared spectrometer (GRIS) is an echelle grating, prism cross-dispersed, spectrometer designed for the 2.3-m Steward Observatory telescope. The cross-dispersed format utilizes a NICMOS 3 HgCdTe detector array for observations in the 0.86-2.5 mu m spectral region. An echelle grating, ruled on both sides, provides resolutions of 3449 and 9439 per slit width, respectively. Rotation of the grating achieves several functions: 1/2 pixel spectrum stepping for full Nyquist sampling, a change in the wavelength regions falling on the detector, and the means for changing grating sides.