NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-20 T12:09:11 PDT
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For refcode 1996ApJS..105..369M:
Retrieve 220 NED objects in this reference.
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NED Abstract

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1996ApJS..105..369M GALACTIC H I COLUMN DENSITIES TOWARD QUASARS AND ACTIVE GALACTIC NUCLEI EDWARD M. MURPHY University of Virginia and National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 FELIX J. LOCKMAN National Radio Astronomy Observatory, Green Bank, WV 24944 ARI LAOR Physics Department, Teclmion, Haifa 32000, Israel AND MARTIN ELVIS Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 Received 1995 November 16; accepted 1996 January 5 ABSTRACT We have determined accurate values of the Galactic neutral hydrogen column density, N_H_, toward 220 quasars and active galactic nuclei from 21 cm H I measurements made on the 140 Foot Telescope (42.7 m). Accurate values of N_H_ have now been obtained for the whole PG bright quasar sample and most quasars that have been observed by ROSAT and the Hubble Space Telescope through mid-1993. The spectra were corrected for stray 21 cm radiation yielding values of NH with a typical uncertainty of 1 x 1O^19^ cm^-2^ for high Galactic latitude directions. The H I column densities will be useful for correcting for interstellar opacity at UV and soft X-ray wavelengths, and for estimating the reddening and extinction toward these objects. Subject headings: Galaxy: structure - radio lines: ISM - X-rays: general
Retrieve 220 NED objects in this reference.
Please click here for ADS abstract

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