Compact high-resolution JR spectrometer for the Columbus Telescope

An infrared, cryogenically-cooled, grating spectrometer has been designed for the Columbus Project (2 X 8.4-m telescopes) and MMT Conversion (6.5-rn). On one barrel of the Columbus Telescope and using a NICMOS3 array of 256 X 256 4Opm HgCdTe detectors, the instrument will project eh pixel to 0.33 arcsec. With a slit of 0.66 arcsec width (2 pixels), the available spectral resolutions will range from λ/Δλ = 670 to 19,000. The optics are hromatic from 1.4 to 5pm, allowing use of a variety of array types. The first version of this instnirnent has been built and fitted with optics that allow its use with the Steward Observatory 1.5-rn and 2.3-rn telescopes. It is relatively inexpensive (< $400K) and compact (~ 0.3 m³). The high spectral resolution in such a compact instrument will be achieved through an echelle grating irnmersed in silicon. We discuss the processing for producing such gratings, including demonstrations that we have conducted on test blanks. We report on the preliminary performance of the prototype instrument and on unique design features that may be useful for other spectrometers.