... quasars

Based on data obtained at the Canada-France-Hawaii telescope which is operated by CNRS of France, NRC of Canada and the University of Hawaii.

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... IRAF

IRAF is the Image Analysis and Reduction Facility made available to the astronomical community by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy (AURA), Inc., under contract with the U.S. National Science Foundation.

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