Performance of the SDSS Spectrographs

The Sloan Digital Sky Survey has spent the first 10 months of 1999 in an instrument commissioning phase of the spectroscopic portion of the survey. Spectroscopic first light was achieved in June. The survey configuration consists of dual 320 fiber-fed spectrographs, each with two cameras in order to achieve a resolution of 1800 with complete wavelength coverage from 3800 Angstroms to 9200 Angstroms. Various aspects of the performance of the two spectrographs are analyzed and compared with the specifications necessary to achieve the goals of the survey. Specifically, analysis of wavelength calibration, resolution, focus, flexure (maximum shift of 0.3 pixels), throughput, placement of spectra on the CCDs, cross talk between fibers on the CCDs, flat-fielding techniques, and guiding stability is presented. Initial results indicate that the spectrographs are performing superbly and meet the required specifications to complete the survey.