Publication: Accurate galactic N(H) values towards quasars and AGN
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Date
1989
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IOP Publishing
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Citation
Elvis, Martin, Belinda J. Wilkes, and Felix J. Lockman. 1989. “Accurate Galactic N(H) Values Towards Quasars and AGN.” The Astronomical Journal 97 (March): 777. doi:10.1086/115022.
Abstract
Integrated Galactic 21-cm column densities toward about 174 quasars and AGN are presented. The data are corrected for stray radiation, using the technique of Lockman et al. (1986). Because of the 21-arcmin beam size of the 140-ft telescope used in the study, the uncertainty in N(H) due to angular variations in the H I of the Galaxy at high latitudes is minimized. The column densities are accurate to about 1 X 10 to the 19th atoms/sq cm, or 5 percent, whichever is larger. Errors above N(H) of about 4 X 10 to the 20th atoms/sq cm are dominated by opacity uncertainties.
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Keywords
Active Galactic Nuclei, Quasars, Sky Surveys (Astronomy), X Ray Sources, Brightness Temperature, H Lines, Heao 2, Radiation Spectra, Signal To Noise Ratios
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