RBS - ROSAT Bright Survey (Schwope et al. 2000)

Overview

The ROSAT Bright Survey (RBS) is an identification program of the more than 2000 X-ray sources at high galactic latitude (absolute latitude b > 30 degrees) with a count rate of more than 0.2 ct/s detected during the ROSAT All-Sky Survey (Voges et al. 1999, A&A, 349, 389). The RBS identification program is more than 99.5% complete. A sub-sample of 931 sources with a count rate of more than 0.2 ct/s in the hard spectral band from 0.5 to 2.0 keV is 100% identified. The total survey area comprises 20391 square degrees at a flux limit of 2.4 x 10^-12 erg/s/cm² in the 0.5 to 2.0 keV band. About 1500 sources of the complete sample were identified by correlating the RBS with the SIMBAD and NED databases. The remaining ~500 sources were identified by low-resolution optical spectroscopy and CCD imaging utilizing various telescopes. The RBS Catalog contains optical and X-ray information for each source, including the most massive complete sample of X-ray selected AGN ever assembled, with a total of 669 members, and a well-populated X-ray selected sample of 302 clusters of galaxies with redshifts of up to 0.52. Three X-ray sources in the RBS remain without optical counterparts, RBS 378, RBS 1223, and RBS 1556. While the first is a possible X-ray transient, the latter two sources are isolated neutron star candidates (Motch et al. 1999, A&A, 351, 177; Schwope et al. 1999, 341, L51). As noted elsewhere, this electronic version of the RBS Catalog has a small number of additions/corrections compared to the published version.

Catalog Bibcode

2000AN....321....1S

References

Schwope, A.D., Hasinger, G., Lehmann, I., Schwarz, R., Brunner, H., Neizvestny, S., Ugryumov, A., Balega, Yu., Trumper, J., and Voges, W. 2000, Astron. Nachr., 321, 1.

Provenance

This database was created by the HEASARC in August 2000 based on a machine-readable table supplied to the HEASARC by Axel Schwope in April 2000. Note that this table is an expanded version of Table 2 in the published paper and contains the following additional parameters: HR2 (hardness_ratio_2), and the Galactic hydrogen column density (nh_21cm).

Updates and Corrections

This electronic version of the RBS Catalog has a few additions/corrections compared to the published version that were made by its authors:

RBS0321: Printed version lists only the F3IV/V star, Fleming identified the
         WD as companion and likely X-ray ID (XID)
RBS0408: Redshift changed from 0.703 to 0.0701 (a typo discovered by A. Edge)
RBS1307: New observation: type now Sy1 (instead of Sy), redshift now 0.171
         (instead of 0.176)
RBS1547: AG Dra now correctly identified as symbiotic binary
RBS1705: Printed version lists only a star of spectral type F8; the soft
         X-ray spectrum suggests an undetected white dwarf as XID
RBS1818: The optical position has been changed to 22 04 17.5, -42 58 14,
         according to Beuermann et al. 1999

Further comments:

RBS88:   Grupe discovered the transient nature of the X-ray activity of this
         Sy-galaxy
RBS1846: Grupe discovered the transient nature of the X-ray activity of this
         Sy-galaxy

Parameters

RBS_Number
A running sequence number for sources in the RBS Catalog.

RXS
The 1RXS Source Name for the X-ray source based on its J2000 position.

RA
The right ascension of the X-ray source, derived from its 1RXS name where it is given to a precision of 0.1 seconds of time, in the requested equinox.

Dec
The declination of the X-ray source, derived from its 1RXS name where it is given to a precision of 1 arcseconds, in the requested equinox.

RA2000_Optical
The right ascension of the optical counterpart to the X-ray source, in J2000 equinox and sexagesimal format.

Dec2000_Optical
The declination of the optical counterpart to the X-ray source, in J2000 equinox and sexagesimal format.

LII
The Galactic longitude of the X-ray source.

BII
The Galactic latitude of the X-ray source.

Offset
The angular offset between the X-ray source and its optical counterpart, in arcsec.

Error_Radius
The one-sigma X-ray positional uncertainty, in arcsec, as given in the 1RXS Catalog. The 90% confidence error radius is 1.65 times sigma, notice.

Count_Rate
The RASS count rate in the total ROSAT PSPC bandpass (0.1 - 2.4 keV), in ct/s.

Hard_Count_Rate
The RASS count rate in the hard ROSAT PSPC bandpass (0.5 - 2.0 keV), in ct/s.

Hardness_Ratio_1
The hardness ratio HR1 = (H-S)/(H+S), where H and S are the counts in the hard (0.5-2.0 keV) and soft (0.1-0.4 keV) spectral bands, respectively.

Hardness_Ratio_2
The hardness ratio HR2 = (H2-H1)/(H1+H2), where H1 and H2 are the count rates in the 0.5-0.9 keV and 0.9-2.0 keV spectral bands, respectively.

NH_21cm
The Galactic hydrogen column density, inferred from 21-cm measurements, in units of 10²⁰ atoms/cm².

Name
The name of the optical counterpart, truncated to 10 characters if longer than 10 characters.

Broad_Class
The broad class of the optical counterpart, according to the scheme below (note that a colon indicates an uncertain id). Plausible IDs based on SIMBAD or NED entered this table essentially without further checking in the original literature. If the broad class or source type of a specific source seemed questionable to the authors based on its specific properties, e.g., an unusual high X-ray flux or X-ray extent, it entered their spectroscopic identification program.

  Broad Class   Explanation

  AGN           Active Galactic Nucleus, X-rays originate from the
                central engine
  GALAX         Normal galaxy without any obvious nuclear activity.
                X-rays originate predominantly from the stellar
                constituents of the galaxy
  CLUST         Cluster of galaxies
  GGRP          Small (compact) group of galaxies
  STAR          Coronal or photospheric emitter of X-rays
  CV            Cataclysmic variable or related object
                (white dwarf accretor)
  XRB           X-ray binary (neutron star or black hole accretor)
  MC            Magellanic Cloud source, not considered in the
                identification program
  VIRGO         X-ray source in the Virgo region, not considered in the
                identification program

Source_Type
For some broad classes, this parameter is used to indicate a specific subtype of object, according to the scheme below (note that a colon indicates an uncertain id). Plausible IDs based on SIMBAD or NED entered this table essentially without further checking in the original literature. If the broad class or source type of a specific source seemed questionable to the authors based on its specific properties, e.g., an unusual high X-ray flux or X-ray extent, it entered their spectroscopic identification program.

  Broad Class   Possible Source_types

  AGN           QSO (Quasi-Stellar Object), BLL or BL (BL Lac object),
                SY1...2 (Seyfert Galaxy of subtype 1...2),
                NLS1 (Narrow-Line Seyfert 1 Galaxy), LINER,
                XTG (X-ray Transient Galaxy), NELG (Narrow Emission-Line Galaxy),
                SRB (Starburst Galaxy)
  GALAX         Hubble type
  STAR          PN (Planetary Nebula), spectral type (for coronal emitters and
                hot stars), WD (White Dwarf), INS (Isolated Neutron Star)
  CV            AM (Am Her star or polar), IP (Intermediate Polar),
                DN (Dwarf Nova), NL (Nova-like variable), SSS (SuperSoft Source),
                SYMB (Symbiotic binary)
  XRB           HMXB or HXB (High-Mass X-ray Binary),
                LMXB (Low-Mass X-ray Binary), XRT (X-Ray Transient)

Redshift
The redshift of the optical counterpart to the X-ray source, if extragalactic.

Redshift_Flag
A flag that is set to ':' if the redshift value is uncertain or '>' if the redshift value is a lower limit.

App_Mag
The apparent optical magnitude of the optical counterpart to the X-ray source.

App_Mag_Flag
A flag that can have the following values, mostly indicative of the information source for the optical magnitude:

  Value     Explanation

    :       uncertain
    >       lower limit
    C       CDS/SIMBAD V-band
    D       CDS/SIMBAD B-band
    N       NED magnitude in the optical range
    R       Red (E) magnitude from APM/ROE scan of POSS/ESO/SERC plate
    B       Blue (O) magnitude from APM/ROE scan of POSS/ESO/SERC plate
    S       Below slit magnitude determined by folding a low-resolution
            spectrum with the sensitivity curve of a V-filter

Flux
The X-ray flux in the 0.5 - 2.0 keV range, in units of erg/s/cm². Assuming a power-law spectrum with a photon index of 2, a count-to-energy conversion factor or ECF for the ROSAT PSPC was computed for the given Galactic column density N_H towards the X-ray source. The flux was then computed using the count rate in the hard band (hard_count_rate) where flux = hard_count_rate/ECF. This approach yields unreliable and inconsistent results for sources with HR1 smaller than -0.4, as even an unabsorbed power law cannot be softer than this limit.

Log_Xray_Opt
The logarithm of the ratio of the X-ray and optical fluxes.

Log_Lx
The logarithm of the X-ray luminosity, in erg/s, for extragalactic sources, calculated using:

        L_x = 4 pi * flux * (c * redshift / H₀)²

and an assumed value of the Hubble Constant H₀ of 50 km/s/Mpc.

Comment_Flag
This is a flag that is set to 'Y' if there is a comment about the particular source at the end of Table 2 in the published version of the RBS Catalog (q.v.).

Class
The Browse classification for the source, derived from the broad_class and source_type parameter values.

Contact Person

Questions regarding the RBS database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:33:36 EDT