- ID:
- ivo://nasa.heasarc/qorgcat
- Title:
- All-Sky Optical Catalog of Radio/X-Ray Sources
- Short Name:
- QuasarOrg
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Quasars.org (QORG) Catalog is an all-sky optical catalog of radio/X-ray sources. The QORG Catalog aligns and overlays the year 2001/2 releases of the ROSAT HRI, RASS, PSPC and WGA X-ray catalogs, the NVSS (2002), FIRST (2003) and SUMSS (2003) radio catalogs, the Veron QSO catalog (2003) and various galaxy/star reference catalogs onto the optical APM and USNO-A catalogs. This catalog displays calculated percentage probabilities for each optical, radio/X-ray associated object of its likelihood of being a quasar, galaxy, star, or erroneous radio/X-ray association. This table contains the main Master QORG catalog (master.dat) and contains all 501,756 radio/X-ray associated optical objects and known quasars which are optically detected in APM/USNO-A. Up to six radio/X-ray catalog identifications are presented for each optical object, plus any double radio lobes (21,498 of these). These are superimposed (and laterally fitted) onto a 670,925,779-object optical background which combines APM and USNO-A data. Other subsets of this master catalog are available at the CDS, including the Free-Lunch catalog, a concise easy-to-read variant of the Master catalog showcasing just one X-ray and/or radio identification for each object, a subset catalog of QSO candidates, and a subset catalog of known QSOs/galaxies/stars. Objects presented in this catalog are those optical APM/USNO-A objects which are associated with X-ray/radio detections, or any optically-found catalogued QSO/AGN/Bl Lac objects, which have confidence levels >40% of being radio/X-ray emitting optical objects. There are 501,756 objects included in all (including 48,285 catalogued quasars), representing the 99.4% coverage of the sky which is available from the APM and USNO-A. Each object is shown as one entry giving the position in equatorial coordinates, red and blue optical magnitudes (recalibrated) and PSF class, calculated probabilities of the object being, separately, a quasar, galaxy, star, or erroneous radio/X-ray association, any radio identification from each of the NVSS, FIRST and SUMSS surveys, including candidate double-lobe detections, any X-ray identification from each of the ROSAT HRI, RASS, PSPC and WGA surveys, including fluxes and field shifts of those identifications, plus, if already catalogued, the object name and redshift where applicable. The QORG catalog and supporting data can be accessed from the catalog home page at <a href="http://quasars.org/qorg-data.htm">http://quasars.org/qorg-data.htm</a> Questions or comments on the catalog contents may be directed to the first author Eric Flesch at eric@flesch.org. The authors request that researchers using this catalog make a small acknowledgement of such use in any published papers which thereby result. This table was created by the HEASARC in November 2004 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/427/387">CDS Catalog J/A+A/427/387</a> file master.dat.gz. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/hrassoptid
- Title:
- Hamburg/RASS Catalog: Optical Identifications
- Short Name:
- HRASS/Opt
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table is a representation of part of the Hamburg/ROSAT All-Sky Survey (RASS) Catalog (HRC) of optical identifications of X-ray sources at high-galactic latitude, namely the list of proposed and possible optical identifications. (The list of the X-ray sources themselves is given in the linked Browse table HRASSCAT). The HRC includes all X-ray sources from the ROSAT Bright Source Catalog (RASS-BSC) with galactic latitude |b| >= 30 degrees and declination Dec >= 0 degrees. In this part of the sky covering ~10,000 square degrees, the RASS-BSC contains 5341 X-ray sources. For the optical identification, the HRC authors used blue Schmidt prism and direct plates taken for the northern hemisphere Hamburg Quasar Survey (HQS) which are now available in digitized form. The limiting magnitudes are 18.5 and 20, respectively. For 82% of the selected RASS-BSC, an identification could be given. For the rest, either no counterpart was visible in the error circle, or a plausible identification was not possible. With ~42%, AGN represent the largest group of X-ray emitters, ~31% have a stellar counterpart, whereas galaxies and cluster of galaxies comprise only ~4% and ~5%, respectively. In ~3% of the RASS-BSC sources, no object was visible on the blue direct plates within 40" around the X-ray source position. The catalog has been used as a source for the selection of (nearly) complete samples of the various classes of X-ray emitters. This table was produced by the HEASARC in February 2005 based on the CDS Catalog table J/A+A/406/353/optical.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rassusnoid
- Title:
- ROSAT All-Sky Survey Bright Source Catalog USNO A2 Cross-Associations
- Short Name:
- RASSUSNOID
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors have quantitatively cross-associated the 18,811 ROSAT All-Sky Survey Bright Source Catalog (RASS/BSC) X-ray sources with optical sources in the USNO A-2 catalog, calculating the probability of unique association (P_id) between each candidate within 75" of the X-ray source position, on the basis of optical magnitude and proximity. They have generated catalogs of RASS/BSC sources for which P_id > 98%, P_id > 90%, and P_id > 50%, which contain 2705, 5492, and 11,301 unique USNO A-2 optical counterparts respectively down to the stated level of significance. Together with identifications of objects not cataloged in USNO A-2 due to their high surface brightness (M31, M32, ...) and optical pairs, they produced a total of 11,803 associations to a probability of P_id > 50%. They also include in this catalog a list of objects in the SIMBAD database within 10" of the USNO A-2 position, as an aid to identification and source classification. This is the first RASS/BSC counterpart catalog which provides a probability of association between each X-ray source and counterpart, quantifying the certainty of each individual association. The catalog is more useful than previous catalogs which either rely on plausibility arguments for association or do not aid in selecting a counterpart between multiple off-band sources in the field. Sources of high probability of association can be separated out, to produce high-quality lists of classes (Seyfert 1/2s, QSOs, RS CVns) desired for targeted study, or for discovering new examples of known classes (or new classes altogether) through the spectroscopic classification of securely identified but unclassified USNO A-2 counterparts. Low P_id associations can be used for statistical studies and follow-on investigation - for example, performing follow-up spectroscopy of the many low-mass stars to search for signatures of coronal emission, or to investigate the relationship between X-ray emission and classes of sources not previously well-studied for their X-ray emissions (such as pulsating variable stars). The authors find that a fraction ~65.8% of RASS/BSC sources have an identifiable optical counterpart, down to the magnitude limit of the USNO A-2 catalog which could be identified by their spatial proximity and high optical brightness. This table was created by the HEASARC in October 2009 based on electronic versions of Tables 9 (USNO counterparts for which P_id > 98%) and 10 (USNO counterparts for which 90% > P_id > 98%) of the reference paper which were obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rassnorsam
- Title:
- ROSAT All-Sky Survey Completely Identified Northern Sample
- Short Name:
- RASS/North
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a completely identified sample of northern ROSAT All-Sky Survey (RASS) X-ray sources, as well as some additional X-ray sources which either had count rates below the adopted limits or were located outside the boundaries of the study areas. It is a catalog of optical identifications of a representative sample of northern (declination > -9 degrees) RASS sources. A full identification has been carried out for a count-rate- and area-limited complete RASS subsample comprising 674 sources. All sources are within six study areas outside the galactic plane (absolute galactic latitude |b| > 19.6 degrees), one area being near the North Galactic Pole and one near the North Ecliptic Pole. This table was created by the HEASARC in August 2003 based on CDS tables J/ApJS/117/319/table1.dat.gz and J/ApJS/117/319/table2.dat.gz. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rixos
- Title:
- ROSAT International X-Ray/Optical Survey Source Catalog
- Short Name:
- RXOS
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The ROSAT International X-Ray/Optical Survey (RIXOS) is a medium-sensitivity survey and optical identification program for X-ray sources which were discovered in ROSAT high Galactic latitude fields (|b| > 28 degrees) and observed with the Position Sensitive Proportional Counter (PSPC) detector. The survey made use of the central 17 arcmin of each ROSAT field. A flux limit of 3 x 10<sup>-14</sup> erg/s/cm<sup>2</sup> (0.5-2.0 keV) was adopted for this survey, and a minimum exposure time of 8000 seconds was required for qualifying ROSAT observations. X-ray sources in the survey are therefore substantially above the detection threshold of each field used, and many contain enough counts to allow the X-ray spectral slope to be estimated. Spectroscopic observations of potential counterparts were obtained of all sources down to the survey limit in 64 fields, totaling a sky area of 15.77 square degrees. Positive optical identifications are made for 94% of the 296 sources thus examined. A further 18 fields (4.44 sq deg), containing 105 sources above the 3 x 10<sup>-14</sup> erg/s/cm<sup>2</sup> survey limit, are completely optically identified to a higher flux of 8 x 10<sup>-14</sup> erg/s/cm<sup>2</sup> (0.5-2.0 keV). Optical spectroscopic data are supplemented by deep CCD imaging of many sources to reveal the morphology of the optical counterparts, and objects too faint to register on Sky Survey plates. The faintest optical counterparts have R ~ 22. This table contains the catalog of the RIXOS sources and their optical identifications. This table was originally ingested by the HEASARC in June 2005 based on CDS table J/MNRAS/311/456/rixos.dat. It was updated in November 2013 shortly after the CDS released an update with the previously inadvertently omitted source RX J111809.9+212554 (RIXOS 123_84) included. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/rosnepoid
- Title:
- ROSAT North Ecliptic Pole Survey Optical Identifications
- Short Name:
- ROSATNEPID
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the ROSAT North Ecliptic Pole (NEP) Survey list of optical identifications. The X-ray data around the NEP from the ROSAT All-Sky Survey (RASS) were used to construct a contiguous area survey which consisted of a sample of 445 individual X-ray sources with fluxes more than ~2x10<sup>-14</sup> erg/cm<sup>2</sup>/s in the 0.5 - 2.0 keV energy band. The NEP survey is centered at RA= 18hr 00min Dec= +66deg 33', and covers a region of 80.7 square degrees at a moderate Galactic latitude b= 29.8 degrees. Hence, the NEP survey is as deep as and covers a comparable solid angle to the ROSAT serendipitous surveys but is also contiguous. The authors identified 99.6% of the sources and determined redshifts for the extragalactic objects. This table contains the optical identifications for the NEP catalog of X-ray sources, including basic X-ray data and properties of the sources. The classification of the optical counterparts to the NEP sources is very similar to that of previous surveys, in particular the Einstein Extended Medium Sensitivity Survey (EMSS). The main constituents of the catalog are active galactic nuclei (AGN) (~49%), either type 1 or type 2 according to the broadness of their permitted emission lines. Stellar counterparts are the second most common identification class (~34%). Clusters and groups of galaxies comprise 14%, and BL Lacertae objects 2%. One non-AGN galaxy and one planetary nebula have also been found. The NEP catalog of X-ray sources is a homogeneous sample of astronomical objects featuring complete optical identification. The data on AGN in this catalog are essentially superceded by the data in the more recent catalog of Mullis et al. (2004, ApJ, 617, 192), available in HEASARC Browse as the ROSNEPOID table (q.v.), in which, inter alia, a corrected count rate to flux conversion and a different cosmology were used. This table was created by the HEASARC in April 2005 based on CDS table J/ApJS/149/29/table3.dat This is a service provided by NASA HEASARC .
