A New High Resolution Charge-Coupled Device Spectrometer for McDonald Observatory

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The University of Texas McDonald Observatory will build a high- resolution spectrograph of novel design incorporating a large echelle grating and prism cross dispersion. Spectra will be projected onto the largest Charge Coupled Device (CCD) image detector available -- the new Tektronix TK2048M. This 55-mm square solid state silicon image detector will produce over 4 million picture elements per exposure. With this combination the entire spectrum of an astronomical object between the atmospheric ultraviolet (UV) cutoff and the near-infrared (IR) limit of CCD sensitivity will be acquired simultaneously at high resolution. A 1-hour exposure will obtain spectra of stars at V magnitude 11 with signal-to-noise 100, while useful spectra can be obtained to magnitude 15 in 3 hours. Major motivations for the new instrumentation are its ability to gather quickly and completely spectra needed to determine CNO, (Carbon, Nitrogen, and Oxygen) abundances in cluster stars and magnesium (Mg) isotopic abundances in old metal-poor dwarfs, stars that are fainter than current limits for these studies. The search for planets around nearby bright stars will rely on the high radial velocity precision enabled by the statistics of large numbers of simultaneously-measured spectral line profiles to determine small periodic motions in the parent star induced by orbital motion of the planet.