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A high signal-to-noise ratio composite quasar spectrum
Francis, Paul J.; Hewett, Paul C.; Foltz, Craig B.; Chaffee, Frederic H.; Weymann, Ray J.; Morris, Simon L.
AA(Cambridge University Institute of Astronomy, England), AB(Cambridge University Institute of Astronomy, England), AC(Multiple Mirror Telescope Observatory, Tucson, AZ), AD(Multiple Mirror Telescope Observatory, Tucson, AZ), AE(Observatoires of the Carnegie Institution of Washington, Pasadena, CA)
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 373, June 1, 1991, p. 465-470. (ApJ Homepage)
Publication Date:
NASA/STI Keywords:
Astronomical Spectroscopy, Emission Spectra, Quasars, Signal To Noise Ratios, Stellar Luminosity, Iron, Line Spectra, Red Shift, Spectral Resolution, Ultraviolet Spectra, Visible Spectrum
Bibliographic Code:


A very high signal-to-noise ratio (S/N of about 400) composite spectrum of the rest-frame ultraviolet and optical region of high luminosity quasars is presented. The spectrum is derived from 718 individual spectra obtained as part of the Large Bright Quasar Survey. The moderate resolution, 4A or less, and high signal-to-noise ratio allow numerous weak emission features to be identified. Of particular note is the large equivalent-width of the Fe II emission in the rest-frame ultraviolet and the blue continuum slope of the composite. The primary aim of this paper is to provide a reference spectrum for use in line identifications, and a series of large-scale representations of the composite spectrum are shown. A measure of the standard deviation of the individual quasar spectra from the composite spectrum is also presented.

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