Spectrophotometric Results from the Copernicus Satellite. I. Instrumentation and Performance

The Princeton telescope-spectrometer on the OAO spacecraft Copernicus scans stellar spectra with a resolution of about 0.05 A between 950 and 1450 A, and twice this in first order between 1650 and 3000A. The pointing during several minutes is steady within 0'!02, and the measured photometric precision in the shorter wavelength range is limited only by the statistics of photon counts, with 14-s counts of about 10 on an unreddened 131 star, mv = 5.0, at 1100 A. In the 165030(X) A wavelength range, phototube noise resulting from cosmic rays makes observations difficult on stars fainter than m = 3.0. Subject headings:instruments - spectra, ultraviolet - spectrophotometry - ultraviolet