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RASSFIRST - ROSAT All-Sky Survey Single FIRST Matches Catalog

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Overview

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: CDS Cat. <VIII/59>) 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 ftp://cdsarc.u-strasbg.fr/pub/cats/J/A+A/356/445/).

Catalog Bibcode

2000A&A...356..445B

References

Radio and X-ray bright AGN: the ROSAT - FIRST correlation
    Brinkmann W., Laurent-Muehleisen S.A., Voges W., Siebert J., Becker R.H.,
    Brotherton M.S., White R.L., Gregg M.D.
   <Astron. Astrophys. 356, 445 (2000)>
   =2000A&A...356..445B

Provenance

This table was created by the HEASARC in March 2012 based on CDS Catalog J/A&A/356/445 file table1.dat, the list of ROSAT All-Sky Survey sources with single FIRST matches.

Parameters

Name
The ROSAT All-Sky Survey designation of the X-ray source as recognized by Simbad, viz., 'RX JHHMM.m+DDMM', where RX stands for ROSAT X-ray source. A different prefix ('RXS') was used in the published version of this paper.

RA
The Right Ascension of the FIRST source assumed to be the radio counterpart of the RASS source, in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the FIRST source assumed to be the radio counterpart of the RASS source, in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the FIRST source assumed to be the radio counterpart of the RASS source.

BII
The Galactic Latitude of the FIRST source assumed to be the radio counterpart of the RASS source.

RASS_First_Offset
The angular distance between the radio (FIRST) and X-ray (RASS) source positions, in arcseconds.

Alt_Name
A common designation for the source obtained from NED (possibly truncated to the first 15 characters).

Object_Type
The classification of the source, using the following types:

      QSO: object with broad (> 1000 km/s) lines and MB < -22.5
        A: narrow line objects (< 1000 km/s) with [OIII]/Hbeta  > 2.0
              and/or [NII]/Halpha  > 0.6
       BA: objects with broad (> 1000 km/s) lines and MB > -22.5
        H: starbursts with [OIII]/Hbeta < 2.0 and/or [NII]/Halpha < 0.6
        G: denotes galaxies (objects with no emission lines and
              Ca II break contrasts > 30%
        B: BL Lacs as defined in Laurent-Muehleisen et al. 1998, ApJS, 118, 127)
        S: stars
       Cl: possible clusters (based on the proximity of a known cluster).
      rad: spectroscopically unclassified radio sources catalogued in
             the ROSAT-Green Bank survey (Brinkmann et al. 1995, A&AS, 109, 147)
  
For previously known objects, the data found in NED were used to avoid confusion. For this reason, some objects are designated as 'Sy', 'Irs', 'Vis', 'UvE', etc.

Ref_Object_Type
The source reference for the object type classification, as follows:

       New: objects classified with spectra taken as part of this program
       Smb: Simbad
       ned: NED
       W00: White et al, 2000, ApJ in press
        id: Becker et al, 2000, subm. to ApJ
  

Redshift
The redshift of the object.

Flux_20_cm
The FIRST 1.4-GHz peak flux density, in mJy.

Flux
The X-ray flux in the 0.1-2.4 keV energy range, in erg s-1 cm-2. The X-ray fluxes were obtained from the measured count rates by assuming an average photon index of Gamma = 2.2 for the underlying X-ray spectrum and the Galactic absorption.

Flux_Error
The rms uncertainty in the X-ray flux, in erg s-1 cm-2. The stated errors refelect the errors in the counting statistics of the RASS sources and do not incorporate the errors due to deviations from the assumed power-law slope or due to additional absorption, or the systematic errors depending on the form of the local X-ray background or on details of the detection algorithm. A reasonable estimate for the total error in the X-ray flux is thus <~ 25%.

Spectral_Index
The power-law photon index Gamma of the X-ray source spectrum estimated using the two ROSAT hardness ratios given by the RASS-II processing, and applying the method described in Brinkmann et al. (1994, A&A, 281, 355), for fixed Galactic absorption. If no values are given, the quality of the data does not allow the determination of a meaningful spectral index.

Spectral_Index_Pos_Err
The positive error in the power-law photon index Gamma of the X-ray source spectrum. These errors were estimated from the errors in the ROSAT hardness ratios (Schartel 1995, PhD thesis).

Spectral_Index_Neg_Err
The negative error in the power-law photon index Gamma of the X-ray source spectrum. These errors were estimated from the errors in the ROSAT hardness ratios (Schartel 1995, PhD thesis).

APM_Emag
The red magnitude of the optical counterpart as measured on the APM scan of the POSS E plate. See Section 2 of the reference paper for a discussion of the accuracy of the APM magnitudes.

APM_Emag_Class
A value for the morphological classification of the optical counterpart in the E-band:

      1 for `non-stellar'
     -1 for `star-like'
      0 for 'noise-like'
      2 for `possible blend'
  

APM_Omag
The blue magnitude of the optical counterpart as measured on the APM scan of the POSS O plate. See Section 2 of the reference paper for a discussion of the accuracy of the APM magnitudes.

APM_Omag_Class
A value for the morphological classification of the optical counterpart in the O-band:

      1 for `non-stellar'
     -1 for `star-like'
      0 for 'noise-like'
      2 for `possible blend'
  

Emag_Extinction
The extinction correction, in magnitudes, in the E-band for the optical counterpart, used as discussed in Section 2 of the reference paper.

First_APM_Offset
The angular distance between the radio (FIRST) and optical source positions, in arcseconds.

Class
The HEASARC Browse object classification, based on the value of the object_type parameter.


Contact Person

Questions regarding the RASSFIRST database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 21-Mar-2012