Access to Astronomical Catalogues

J/A+AS/139/575      RASS AGN sample                          (Wei+, 1999)
An AGN sample with high X-ray-to-optical flux ratio from RASS. I.
The optical identification.
       Wei J.Y., Xu D.W., Dong X.Y., Hu J.Y.
      <Astron. Astrophys. Suppl. Ser. 139, 575 (1999)>
      =1999A&AS..139..575W
ADC_Keywords: X-ray sources ; Active gal. nuclei ; Magnitudes ; Redshifts

Mission_Name: ROSAT

Keywords: surveys - X-rays: general - X-rays: galaxies - galaxies: active


Abstract:
    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(fX/fopt), 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.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table2.dat        98      184   X-ray identification information


See also:
    IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
    I/243 : The PMM USNO-A1.0 Catalogue (Monet 1997)


Byte-by-byte Description of file: table2.dat

   Bytes Format Units   Label   Explanations

   1- 15  A15   ---     1RXSJ   ROSAT name
  17- 18  I2    h       RAh     Right ascension (J2000) (1)
  20- 21  I2    min     RAm     Right ascension (J2000)
  23- 27  F5.2  s       RAs     Right ascension (J2000)
      29  A1    ---     DE-     Declination sign (J2000)
  30- 31  I2    deg     DEd     Declination (J2000)
  33- 34  I2    arcmin  DEm     Declination (J2000)
  36- 39  F4.1  arcsec  DEs     Declination (J2000)
  41- 42  I2    arcsec  PE      ? ROSAT X-ray position error (2)
  44- 47  F4.1  arcsec  Sep     Angular separation between the X-ray source
                                 and the proposed optical counterpart
  49- 53  F5.3  ct/s    CR      ? ROSAT total count rate (2)
  55- 59  F5.2  ---     HR1     ? Hardness ratio 1 (3)
  61- 65  F5.2  ---     HR2     ? Hardness ratio 2 (3)
  67- 69  I3    arcsec  Ext     ? Extent  (2)
  71- 74  F4.1  mag     Rmag    R magnitude (4)
  76- 79  F4.1  mag     Bmag    B magnitude (4)
  81- 86  A6    ---     ID      Classification of the optical counterpart (5)
  88- 92  F5.3  ---     z       ? Average redshift for extragalactic counterpart
  94- 98  F5.1  mag     BMAG    ? Absolute B magnitude

Note (1): Position of the proposed optical counterpart

Note (2): Value as given in RASS-BSC, Cat. IX/10

Note (3): HR1=(B-A)/(B+A), where A means the count rate in the energy range
           0.1-0.4 keV and B in the energy range 0.5-2.0 keV.
          HR2=(D-C)/(D+C), where C means the count rate in the energy range
           0.5-0.9 keV and D in the energy range 0.9-2.0 keV.
Note (4): Magnitudes obtained from USNO-A1.0 with an accuracy between
           0.25 and 0.40 magnitudes depending on the declination (Monet et al.,
           1996, Cat. I/243)
Note (5): The abbreviations have the following meanings:
           QSO: quasi-stellar object (unresolved or resolved object with
                 MB < 23 showing a Seyfert 1 spectrum)
           Sey: Seyfert galaxy
            BL: BL Lac object
        BL can: BL Lac candidate
            CL: cluster of galaxies
            WD: white dwarf
            CV: cataclysmic variable star
             M: M star


History: From A&AS electronic version

(End)                                          Patricia Bauer [CDS]  11-Feb-2000