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Description
This table contains a subset of the results of a correlation of the ROSAT All-Sky Survey (RASS) with the April 1997 release of the VLA 20-cm Faint Images of the Radio Sky at Twenty cm (FIRST: <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VIII/59">CDS Cat. <VIII/59></a>) Catalog. It focusses on the analysis of the 843 X-ray sources which have unique radio counterparts. The majority of these objects (84%) have optical counterparts on the POSS 1 plates. Approximately 30% have been previously classified and the authors obtain new spectroscopic classifications for 85 sources by comparison with the ongoing FIRST Bright Quasar Survey and 106 additional sources from their own new spectroscopic data. Approximately 51% of the sources are presently classified, and the majority of the unclassified objects are optically faint. The newly classified sources are generally radio weak, exhibiting properties intermediate with previous samples of radio- and X-ray-selected AGN. This also holds for the subsample of 71 BL Lacs which includes many intermediate objects. The 146 quasars show no evidence for a bimodal distribution in their radio-loudness parameter, indicating that the supposed division between radio-quiet and radio-loud AGN may not be real. The X-ray and radio luminosities are correlated over two decades in radio luminosity, spanning the radio-loud and radio-quiet regimes, with radio-quiet quasars showing a linear correlation between the two luminosities. Many of the sources show peculiar or unusual properties which call for more detailed follow-up observations. In their paper (Table 2), the authors also give the X-ray and radio data for the 518 X-ray sources for which more than one radio object is found. Because of the difficulties inherent in identifying optical counterparts to these complex sources, they do not consider these data in the current analysis, and they are not included in the present table (but are available at <a href="http://cdsarc.u-strasbg.fr/ftp/cats/J/A+A/356/445/">http://cdsarc.u-strasbg.fr/ftp/cats/J/A+A/356/445/</a>). This table was created by the HEASARC in March 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/356/445">CDS Catalog J/A+A/356/445</a> file table1.dat, the list of ROSAT All-Sky Survey sources with single FIRST matches. This is a service provided by NASA HEASARC .
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