Subject: active galactic nuclei / Facility: ROSAT / Rights: public

ID:: ivo://CDS.VizieR/J/A+A/310/384
Title:: Optical brightness of 3 ROSAT Seyfert galaxies
Short Name:: J/A+A/310/384
Date:: 21 Oct 2021
Publisher:: CDS
Description:: The printed version of this paper describes the X-ray and optical properties of four new active galaxies discovered in the ROSAT All-Sky Survey. While one object (RX J1257.5+2412) is identified as a BL Lac object, the other three (RX J1239.3+2431, RX J1225.7+2055, and RX J1250.2+1923) are narrow line Seyfert 1 galaxies. Three of these four objects are bright enough to be studied on archival photographic plates of Sonneberg Observatory. The present list contains the individual brightness measurements of these objects all of which turned out to be variable on timescales of weeks to years. Some lightcurves (long-term as well as short-term) are given in the printed version.

ID:: ivo://CDS.VizieR/J/A+AS/139/575
Title:: RASS AGN sample
Short Name:: J/A+AS/139/575
Date:: 21 Oct 2021
Publisher:: CDS
Description:: We present the first results of a program to identify the unknown bright active galactic nuclei (AGN) in the ROSAT All Sky Survey Bright Source Catalog (RASS-BSC). We have used logC+0.4R as an alternative expression for log(f_X_/f_opt_), where C is X-ray count rate and R stands for R magnitude. Then a high X-ray-to-optical flux ratio criterion has been used to select an AGN sample with 165 unidentified X-ray sources for optical spectroscopy. Those 165 X-ray sources have been identified in the following classes: 115 emission line AGN (QSOs and Seyferts), 2 BL Lac objects and 4 BL Lac candidates, 22 clusters of galaxies, 12 Galactic stars and 10 objects remain unidentified. This represent a success rate of about 73% for detecting AGN using our selection criteria. Plausibility is based upon the optical classification and X-ray characteristics of the sources.

ID:: ivo://CDS.VizieR/J/A+AS/109/147
Title:: ROSAT AGN content
Short Name:: J/A+AS/109/147
Date:: 21 Oct 2021
Publisher:: CDS
Description:: The cross-correlation of the source list from the ROSAT All-Sky Survey with the 5 GHz Green Bank survey yields a list of 2127 objects. About two thirds of them are optically unidentified. The majority of the objects with known optical counterparts are quasars and radio galaxies, most of them detected in X-rays for the first time. In this paper we present a list of the previously optically identified objects with their main characteristics and discuss their general (bulk) properties. We find strong correlations between luminosities in the radio, optical, and X-ray bands which differ for quasars and radio galaxies.

ID:: ivo://CDS.VizieR/IX/32
Title:: ROSAT Bright Survey
Short Name:: IX/32
Date:: 21 Oct 2021
Publisher:: CDS
Description:: The ROSAT Bright Survey (RBS, table "rosat.dat") aims to completely optically identify the 2072 brightest sources detected in the ROSAT all-sky survey (Cat. <IX/10>) at galactic latitudes |b|>30{deg} (excluding LMC, SMC, Virgo cluster), with countrate above 0.2s^-1^; this program is 99.5% complete, and a sub-sample of 931 sources with countrate above 0.2s^-1^ in the hard spectral band between 0.5 and 2.0keV is 100% identified. The total survey area comprises 20391{deg}^2^ at a flux limit of 2.4x10^-12^erg/cm^2^/s in the 0.5-2.0keV band. Tables 1 and 3 examine the "RHS" sub-sample of 66 bright point-like ROSAT survey sources with almost hard PSPC spectra (hardness ratio HR1>0.5) which could be nearly completely identified by low-resolution optical spectroscopy with the following breakdown into object classes: 31 Seyfert galaxies (20 Sy1), 22 BL Lac candidates, 5 clusters of galaxies, 1 cataclysmic variable, and 5 bright stars. Only one object remained unidentified and one X-ray source was a spurious detection.

ID:: ivo://CDS.VizieR/J/A+A/309/81
Title:: X-ray properties of AGN
Short Name:: J/A+A/309/81
Date:: 21 Oct 2021
Publisher:: CDS
Description:: ROSAT spectra of 86 Active Galactic Nuclei (AGN) with a broad range of optical FeII strengths have been analyzed. The results of the spectral analysis have been combined with optical and radio data as well as with optical emission line properties collected from the literature to understand the origin of the strong FeII emission and the nature of the soft X-ray excess.

ID:: ivo://CDS.VizieR/J/A+A/350/805
Title:: X-ray selected ROSAT AGN spectra
Short Name:: J/A+A/350/805
Date:: 21 Oct 2021
Publisher:: CDS
Description:: We present the emission line properties of a sample of 76 bright soft X-ray selected ROSAT Active Galactic Nuclei. All optical counterparts are Seyfert 1 galaxies with rather narrow permitted lines, strong optical FeII line blends, and weak forbidden lines. By selection, they also have steep soft X-ray spectra when compared with typical Seyfert 1 galaxies. We discuss possible origins of these peculiar trends employing detailed correlation analyses, including a Principal Component Analysis. The optical spectra are presented in the Appendix.

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