WARPS - Wide Angle ROSAT Pointed Survey, First Phase (WARPS-I)
The Wide Angle ROSAT Pointed Survey, First Phase (WARPS-I) table is a catalog
which contains optical identifications for objects found in a serendipitous
survey of relatively deep, pointed ROSAT observations for clusters of
galaxies. The X-ray source detection algorithm used by WARPS is Voronoi
Tessellation and Percolation (VTP), a technique which is equally sensitive to
point sources and to extended sources of low surface brightness. WARPS-I is
based on the central regions of 86 ROSAT PSPC fields, covering an area of
16.2 square degrees. The X-ray source screening and optical identification
process for WARPS-I yielded 34 clusters at 0.06<z<0.75. Twenty-two of these
clusters form a complete, statistically well-defined sample drawn from 75 of
these 86 fields, covering an area of 14.1 square degrees, with a flux limit
of F(0.5-2.0keV) = 6.5x10^-14 erg/cm^2/s. This sample can be used to study
the properties and evolution of the gas, galaxy and dark matter content of
clusters and to constrain cosmological parameters.
The WARPS survey. VI. Galaxy cluster and source identifications from phase I.
Perlman E.S., Horner D.J., Jones L.R., Scharf C.A., Ebeling H., Wegner G.,
<Astrophys. J. Suppl. Ser. 140, 265 (2002)>
This online catalog was created by the HEASARC in May 2003 based on
machine-readable versions of tables 2, 3, 4 and 5 of Perlman et al. (2002)
that were obtained from the CDS.
The HEASARC has combined data from 4 separate tables from Perlman et al. (2002)
into this database table. There are some changes in this HEASARC tabular version
and some additional parameters that have been added compared to the published
version: (i) The prefix used for the names of sources is WARPS rather than
WARP as in the published version: the former version is the one recommended
by the Dictionary of Astronomical Nomenclature; (ii) The HEASARC has added a
new parameter, table_id, which indicates from which table a particular entry
originates (2, 3 or 5); (iii) The HEASARC has added a new parameter,
flux_limited_sample, which indicates whether or not a given source is part of
the statistically complete, flux-limited sample, i.e., is listed in Table 4
of the published paper; and (iv) the HEASARC has set values of the parameter
spectra_flag which were "..." in the original Tables 2 and 3 to "N" in this
present table; for sources which were in Table 5 of the published paper but
were not listed in either Tables 2 or 3, the HEASARC has left spectra_flag
The assigned source name. The prefix used for the names of sources is
WARPS (rather than WARP as in the published version), as recommended
by the Dictionary of Astronomical Nomenclature.
The ROSAT pointing which contains the source.
The Right Ascension of the X-ray source in the selected equinox.
The typical positional error is 15 arcseconds. The RA was listed in
J2000 coordinates and to a precision of 0.1 seconds of time in the
original published tables.
The Declination of the X-ray source in the selected equinox.
The typical positional error is 15 arcseconds. The Declination was listed
in J2000 coordinates and to a precision of 1 arcsecond in the original
The Galactic Longitude of the X-ray source.
The Galactic Latitude of the X-ray source.
The raw count rate obtained from the Voronoi Tessellation
and Percolation (VTP) detection algorithm, in counts per second.
The corrected (i.e., total) count rate as obtained from the
Voronoi Tessellation and Percolation (VTP) detection algorithm, in counts
The Galactic Hydrogen column density from Dickey & Lockman
(1990, ARAA, 28, 215), in units of H atoms cm^2.
The unabsorbed 0.5-2.0 keV X-Ray flux in the 0.5 - 2.0 keV band,
in units of erg/cm^2/s. For clusters of galaxies, the flux was calculated
using the same iterative method which was used by Ebeling et al. (1998, MNRAS,
301, 881). For some clusters, this flux may include a component from
contaminating sources (e.g., AGNs): see Section 4.4 of the published paper
for details for each cluster. The authors assumed a Raymond-Smith spectrum
with a redshift appropriate for each cluster and a metal abundance of 0.3
solar. The temperature of the model was derived iteratively by constraining
the cluster to obey the observed L-T relation (White, Jones, & Forman 1997,
MNRAS, 292, 419). Fluxes were obtained for AGNs and unidentified sources
assuming a power-law spectrum with F_nu ~ nu^-1, where nu is frequency. The
fluxes for sources identified as stars were calculated assuming a Raymond-Smith
model with a temperature of 2 x 10^6 K and with no correction for Galactic
hydrogen column density.
The logarithm of the rest-frame source luminosity in the 0.5-2.0 keV
band, in units of erg/s, derived in the same manner as the flux. Values of
q_0 = 0.5 and H_0 = 50 km s^-1 Mpc^-1 were assumed.
The core radius of the cluster, in arcseconds. Note that this
is very crude as it is based on ROSAT data which in most cases barely resolve
The source extent parameter, defined as the ratio
S_King_/S_point as discussed in Section 2.1 of the published paper.
The imaging status of the source. The letters indicates
the band of the optical image(s) obtained, B, I or R.
The status of the spectroscopic follow-up, where a "Y"
indicates that spectra were taken for this source. Note that the HEASARC has
set values of this parameter which were "..." in the original published Tables
2 and 3 to "N"; also that for sources which were in Table 5 of the published
paper but which were not listed in either Tables 2 or 3, the HEASARC has left
the value blank.
The identification of the source (e.g., cluster, AGN, star).
Identifications in lower case were identified based on the literature
(primarily using NED and SIMBAD), while upper case IDs are based on WARPS
optical follow-up observations. Sources listed as blends are briefly discussed
in the notes parameter.
The redshift of the source, if known,
This parameter is a flag which is set to ":" to indicate
that the redshift value is uncertain or to "]" if the redshift was
estimated photometrically. Such individual cases are discussed in Section 4.4
of the published paper.
The number of galaxy redshifts used to derive the cluster
The spectral type, given for sources that have been identified
This parameter contains some additional flags, as follows: a "c"
indicates that the cluster is contaminated or possibly contaminated by other
sources; a "<" indicates that the cluster flux falls below the limit for
inclusion in the statistically complete, flux-limited sample; a "?" indicates
a possible cluster or group for which optical follow-up was not completed,
usually because it was below the flux limit; an "8" indicates that the cluster
was found in a field targeted at another cluster; a "b" indicates that this
field was dropped due to high background. See the notes in Section 4.4 of
the published paper for more details on the flagged sources.
This parameter contains alternate names and other notes. Sources
listed as SHARC appear in the SHARC Bright Survey catalog (Romer et al. 2000,
ApJS, 126, 209). Sources listed as VMF correspond to sources in the CfA 160
square degree survey of Vikhlinin et al. (1998, ApJ, 498, 21). Sources listed
as RIXOS correspond to sources in the RIXOS survey catalog (Mason et al. 2000,
MNRAS, 311, 456). NVSS (Condon et al. 1998, AJ, 115, 1693) and FIRST (e.g.,
White et al. 1997, ApJ, 475, 479) radio sources are also indicated.
The HEASARC created this new parameter in order to indicate from
which table a particular entry originates: it is set to 2 for sources listed
in Table 2 of the published paper, the WARPS-I Source Catalog, to 3
for sources listed in Table 3 of the published paper, the "Other Sources",
and to 5 for sources listed in Table 5 of the published paper, the
WARPS-I Additional Clusters and Candidates, which were not present in either
Tables 2 or 3.
The HEASARC created this new parameter in order to
indicate whether or not a source is part of the WARPS-I statistically complete,
flux-limited sample, i.e., is listed in Table 4 of the published paper.
The HEASARC Browse object classification, based on the source_type
and spect_type parameter values, if available.
Questions regarding the WARPS database table can be addressed to the
HEASARC User Hotline.
If you have any problems, please consult the help
page or mail firstname.lastname@example.org