RASSBCS ivo://nasa.heasarc/rassebcs NASA/GSFC HEASARC Ebeling et al. 2026-04-24 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Cluster of Galaxies This table contains the ROSAT All-Sky Survey (RASS) Brightest Cluster Sample (BCS) and the Low-Flux Extension, which together form the Extended BCS (eBCS). The main BCS, which was presented in Ebeling et al. (1998, MNRAS, 301, 881; Paper I), is a 90% flux-complete sample of the 201 X-ray-brightest clusters of galaxies in the northern hemisphere (Dec >=0 degrees), at high Galactic latitudes (|b| >= 20 degrees), with measured redshifts z <= 0.3 and X-ray fluxes higher than 4.4 x 10<sup>-12</sup> erg/cm<sup>2</sup>/s in the 0.1 - 2.4 keV band. This sample, called the ROSAT Brightest Cluster Sample, is selected from RASS data and is the largest X-ray-selected cluster sample compiled to the publication date (1998). In addition to Abell clusters which form the bulk of the sample, the BCS also contains the X-ray-brightest Zwicky clusters and other clusters selected from their X-ray properties alone. Effort has been made to ensure the highest possible completeness of the sample and the smallest possible contamination by non-cluster X-ray sources. X-ray fluxes were computed using an algorithm tailored for the detection and characterization of X-ray emission from galaxy clusters. These fluxes are accurate to better than 15% (mean 1-sigma error). The low-flux extension of the X-ray-selected ROSAT Brightest Cluster Sample was published in Ebeling et al. (2000, MNRAS, 318, 333; Paper IV). Like the original BCS and employing an identical selection procedure, the BCS extension is compiled from ROSAT All-Sky Survey (RASS) data in the northern hemisphere (Dec >=0 degrees) and at high Galactic latitudes (|b| >= 20 degrees). It comprises 99 X-ray-selected clusters of galaxies with measured redshifts z <= 0.3 (as well as eight more at z > 0.3) and total fluxes between 2.8 x 10<sup>-12</sup> and 4.4 x 10<sup>-12</sup> erg/cm<sup>2</sup>/s in the 0.1 - 2.4keV band (the latter value being the flux limit of the original BCS). The extension can be combined (as it has been in this HEASARC table) with the main sample published in 1998 to form the homogeneously selected extended BCS (eBCS), the largest and statistically best understood cluster sample to emerge from the RASS to date. The nominal completeness of the combined sample (defined with respect to a power-law fit to the bright end of the BCS log N -log S distribution) is relatively low at 75% (compared with 90% for the high-flux sample of Paper I). However, just as for the original BCS, this incompleteness can be accurately quantified, and thus statistically corrected for, as a function of X-ray luminosity and redshift. In addition to its importance for improved statistical studies of the properties of clusters in the local Universe, the low-flux extension of the BCS is also intended to serve as a finding list for X-ray-bright clusters in the northern hemisphere which the authors hoped will prove useful in the preparation of cluster observations to be made with the next generation of X-ray telescopes such as Chandra and XMM-Newton. This table was created by the HEASARC in August 2005 based on the merger of 2 CDS tables, J/MNRAS/301/881/table3.dat.gz (the main sample) and J/MNRAS/318/333/table1.dat.gz (the low-flux extension). This is a service provided by NASA HEASARC . 2000MNRAS.318..333E https://heasarc.gsfc.nasa.gov/W3Browse/all/rassebcs.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=rassebcs& GET text/xml 180 99999 true 229.068 0.089 0.05 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=rassebcs GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_rassebcs&Action=More+Options&Action=Parameter+Search&ConeAdd=1 ROSAT 0.05 X-ray public rassebcs ROSAT All-Sky Survey Extended Brightest Cluster Sample name Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable count_rate Final PSPC Count Rate in PHA Channels 11 to 235 Based on Original VTP Count Rate ct/s phot.count;em.X-ray double nullable count_rate_error RMS Uncertainty in Count Rate ct/s stat.error;phot.count;em.X-ray double nullable redshift Measured Redshift src.redshift double nullable lx Intrinsic X-Ray Luminosity in 0.1-2.4 keV Band (Cluster Rest Frame) erg/s phys.luminosity;em.X-ray double nullable angular_radius Equivalent Radius of the Source Detected by VTP (arcmin) arcmin phys.angSize;src float nullable vtp_count_rate PSPC Count Rate in PHA Channels 11 to 235 Originally Detected by VTP ct/s phot.count;em.X-ray double nullable tx_flag Flag [e] Indicates Temperature Is Estimated meta.note;phys.temperature char nullable exposure Total RASS Exposure Time (s) s time.duration;obs.exposure short nullable bii Galactic Latitude degree pos.galactic.lat double nullable lii Galactic Longitude degree pos.galactic.lon double nullable redshift_ref Reference Code for Redshift Value meta.ref;src.redshift char nullable notes Source Notes meta.note char nullable tx Intra-Cluster Gas Temperature (keV) keV phys.temperature float nullable flux Unabsorbed X-Ray Energy Flux in 0.1-2.4 keV Band (erg/s/cm^2) erg/s/cm^2 phot.flux;em.X-ray double nullable sample Indicates Published Table from Which Entry Originates: main=Table3, extd=Table1 meta.note char nullable nh Hydrogen Column Density from Stark et al. 1992 (cm^-2) H-atoms/cm^2 phys.columnDensity double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable