- ID:
- ivo://nasa.heasarc/ascaegclus
- Title:
- ASCA Elliptical Galaxies and Galaxy Clusters Catalog
- Short Name:
- ASCAEGCLUS
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Utilizing ASCA archival data of about 300 objects - elliptical galaxies, groups, and clusters of galaxies - the authors performed systematic measurements of the X-ray properties of hot gas in their systems, and compiled them in this study. The steepness (power-law slope) of the luminosity-temperature (L-T) relation, L<sub>X</sub> ~ kT<sup>alpha</sup>, in the range of kT ~ 1.5 - 15 keV is alpha = 3.17 +/- 0.15, consistent with previous measurements. In the relation, the authors find two breaks at around intracluster medium (ICM) temperatures of 1 keV and 4 keV: alpha = 2.34 +/- 0.29 above 4 keV, 3.74 +/- 0.32 in the 1.5 to 5 keV range, and 4.03 +/- 1.07 below 1.5 keV. Two such breaks are also evident in the temperature and size relation. The steepness in the L-T relation at kT > 4 keV is consistent with the scale-relation derived from the CDM model, indicating that the gravitational effect is dominant in richer clusters, while poorer clusters suffer non-gravity effects. The steep L-T relation below 1 keV is mostly attributed to X-ray faint systems of elliptical galaxies and galaxy groups. The authors find that the ICM mass within the scaling radius R<sub>1500</sub> (the radius within which the averaged mass density is 1500 times higher than the critical density) follows the relation of M<sub>gas</sub> ~ T<sup>(2.33+/-0.07)</sup> from X-ray faint galaxies to rich clusters. Thus, the authors speculate that even such X-ray faint systems contain large-scale hot gas, which is too faint to detect. For this project, the authors utilized all of the ASCA data of elliptical galaxies and clusters of galaxies. Several clusters were observed more than once, and they chose the observation with the longest exposure. The total number of objects that the authors identified as elliptical galaxies and clusters was 313, and these are listed in this table. Some of the objects could not be utilized for deriving various correlations, due to either having an unknown redshift (17 objects), an insignificant detection (13 objects listed below), or contamination of the environmental X-ray emission, such as cluster emission around non-cD elliptical galaxies (10 objects: NGC 4472, NGC 4406, NGC 4374, NGC 1404, NGC 499, NGC 6034, NGC 2865, NGC 4291, CL 2236-04 and RX J1031.6-2607). Thus, the authors analyzed the ASCA data for 292 objects, among which were ~ 50 elliptical galaxies and galaxy groups. In this study, the authors assumed the Hubble constant to be 50 h<sub>50</sub> km s<sup>-1</sup> Mpc<sup>-1</sup> and q<sub>0</sub> to be 0. Table 1 of the reference paper (reproduced below) lists the 13 clusters for which only 90% confidence level upper limits to the flux in the observer's frame are available: <pre> Name Flux (0.5 - 2 keV) Upper Limit (erg/s/cm<sup>2</sup>) NGC 5018 9.8 x 10<sup>14</sup> GHO 1322+3114 1.3 x 10<sup>13</sup> J1888.16CL 5.9 x 10<sup>14</sup> CL 0317+1521 4.5 x 10<sup>14</sup> MS 1512.4+3647 1.0 x 10<sup>12</sup> PRG 38 6.9 x 10<sup>14</sup> SCGG 205 6.9 x 10<sup>14</sup> RGH 101 9.1 x 10<sup>14</sup> 3C 184 8.5 x 10<sup>14</sup> RX J1756.5+6512 1.6 x 10<sup>13</sup> 3C 324 5.4 x 10<sup>14</sup> PDCS 01 2.8 x 10<sup>14</sup> MS 0147.8-3941 5.0 x 10<sup>14</sup> </pre> This table was created by the HEASARC in December 2011 based on CDA Catalog J/PASJ/56/965 files table3.dat, table4.dat, table5.dat, table6.dat and table7.dat. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/arxa
- Title:
- Atlas of Radio/X-Ray Associations (ARXA)
- Short Name:
- ARXA
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Atlas of Radio/X-Ray Associations (ARXA) is a compendium of all cataloged or APM/USNO-A optical objects which are found to be associated with XMM-Newton, Chandra, RASS, HRI, PSPC or WGACAT X-ray detections, or with NVSS, FIRST or SUMSS radio detections. All detections are listed, plus double radio lobes where found. The source number counts are: <pre> Optical objects - 602,570. NVSS - 266,148 core associations, plus 8309 double lobes. FIRST - 173,383 core associations, plus 12,844 double lobes. SUMSS - 59,138 core associations, plus 2529 double lobes. XMM associations - 57,778. Chandra associations - 32,951. ROSAT RASS - 47,486. ROSAT HRI - 15,523. ROSAT PSPC - 35,607. WGA - 24,226. </pre> Each optical object is given as one entry in this catalog, containing the sky coordinates, the object name (from the literature where available), APM and USNO-A sourced red and blue photometry, redshift, the source catalogs for the name and redshift, the calculated odds that the object is a quasar, galaxy, star, or erroneous association, and the radio & X-ray identifiers, up to 10 of them possible although usually just 1 or 2. This catalog supersedes the previous similar compilation by the same author, the Quasars.org (QORG) Catalog, called QORGCAT in the HEASARC's Browse (see <a href="http://quasars.org/qorg-data.htm">http://quasars.org/qorg-data.htm</a>). Questions or comments on ARXA may be directed to eric@flesch.org. See also: <pre> APM home page <a href="http://www.ast.cam.ac.uk/~apmcat">http://www.ast.cam.ac.uk/~apmcat</a> USNO-A home page <a href="http://www.nofs.navy.mil/">http://www.nofs.navy.mil/</a> NVSS home page <a href="http://www.cv.nrao.edu/nvss/">http://www.cv.nrao.edu/nvss/</a> FIRST home page <a href="http://sundog.stsci.edu/">http://sundog.stsci.edu/</a> SUMSS home page <a href="http://www.astrop.physics.usyd.edu.au/SUMSS/index.html">http://www.astrop.physics.usyd.edu.au/SUMSS/index.html</a> XMM-Newton home page <a href="http://xmmssc-www.star.le.ac.uk">http://xmmssc-www.star.le.ac.uk</a> HRI & PSPC home page <a href="http://www.mpe.mpg.de/ROSAT/">http://www.mpe.mpg.de/ROSAT/</a> WGA home page <a href="http://wgacat.gsfc.nasa.gov/wgacat/wgacat.html">http://wgacat.gsfc.nasa.gov/wgacat/wgacat.html</a> RASS-FSC home page <a href="http://www.xray.mpe.mpg.de/rosat/survey/rass-fsc">http://www.xray.mpe.mpg.de/rosat/survey/rass-fsc</a> RASS-BSC home page <a href="http://www.xray.mpe.mpg.de/rosat/survey/rass-bsc">http://www.xray.mpe.mpg.de/rosat/survey/rass-bsc</a> Chandra home page <a href="http://chandra.harvard.edu">http://chandra.harvard.edu</a> XAssist home page <a href="http://xassist.pha.jhu.edu/zope/xassist">http://xassist.pha.jhu.edu/zope/xassist</a> (XMMX & CXOX sources are from XAssist) </pre> If using this catalog in published research, please add a small mention in the acknowledgements. This table is based on research which made use of the NASA/IPAC Extragalactic Database (NED) operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. This online catalog was created by the HEASARC in January 2010 based on a machine-readable table obtained from the author's ARXA web site at <a href="http://quasars.org/arxa.htm">http://quasars.org/arxa.htm</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cfa2s
- Title:
- CfA Redshift Survey: South Galactic Cap Data
- Short Name:
- CfARed.S.
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Center for Astrophysics (CfA) Redshift Survey South Galactic Cap (CFA2S) Catalog contains redshifts for a sample of about 4300 galaxies with blue (Zwicky B(0) type) magnitude <= 15.5 covering the range from 20 h to 4h in right ascension and from -2.5 deg to 90 deg in declination. This sample is complete for all galaxies in the merge of the Zwicky et al. and Nilson catalogs in the south Galactic cap. Redshifts for 2964 of these were measured as part of the second CfA Redshift Survey. The data reveal large voids in the foreground and background of the Perseus-Pisces Supercluster. The largest of these voids lies at a mean velocity ~ 8000km/s, has diameter of ~ 5000km/s, and is enclosed by a complex of dense structures. The large structure known as the Perseus-Pisces Supercluster forms the near side of this complex. On the far side of this large void, at a mean velocity of ~ 12000km/s, there is another coherent dense wall. The structures in this survey support the view that galaxies generally lie on surfaces surrounding or nearly surrounding low-density regions or voids. This table was created by the HEASARC in March 2005 based on CDS table J/ApJS/121/287/cfa2s.dat.gz This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ccosrssfag
- Title:
- Chandra COSMOS Radio-Selected Star-Forming Galaxies and AGN Catalog
- Short Name:
- CCOSRSSFAG
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- X-ray surveys contain sizable numbers of star-forming galaxies, beyond the AGN which usually make up the majority of detections. Many methods to separate the two populations are used in the literature, based on X-ray and multi-wavelength properties. The authors aim at a detailed test of the classification schemes and to study the X-ray properties of the resulting samples. They build on a sample of galaxies selected at 1.4 GHz in the VLA-COSMOS survey, classified by Smolcic et al. (2008, ApJS, 177, 14) according to their optical colors and also observed by Chandra. A similarly selected control sample of AGN is also used for comparison. The authors review some X-ray based classification criteria and check how they affect the sample composition. The efficiency of the classification scheme devised by Smolcic et al. (2008) is such that ~30% of composite/misclassified objects are expected because of the higher X-ray brightness of AGN with respect to galaxies. The latter fraction is actually 50% in the X-ray detected sources, while it is expected to be much lower among X-ray undetected sources. Indeed, the analysis of the stacked spectrum of undetected sources shows, consistently, strongly different properties between the AGN and galaxy samples. X-ray based selection criteria are then used to refine both samples. The radio/X-ray luminosity correlation for star-forming (SF) galaxies is found to hold with the same X-ray/radio ratio valid for nearby galaxies. Some evolution of the ratio may be possible for sources at high redshift or high luminosity, though it is likely explained by a bias arising from the radio selection. Finally, in their paper the authors discuss the X-ray number counts of star-forming galaxies from the VLA- and C-COSMOS surveys according to different selection criteria, and compare them to the similar determination from the Chandra Deep Fields. The classification scheme proposed here may find application in future works and surveys. This table contains the catalogs of radio-selected SF- and AGN-candidate sources with an X-ray detection in C-COSMOS which were contained in Tables 2 and 3 of the reference paper, respectively. The HEASARC has merged these into a single table, adding a new parameter sample which is set to 'SFG' for radio-selected SF-candidate sources from Table 2 and to 'AGN' for the AGN-candidate sources from Table 3. This table was created by the HEASARC in June 2012 based on CDS table J/A+A/542/A16 files table2.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cosmosvlba
- Title:
- COSMOS Field VLBA Observations 1.4-GHz Source Catalog
- Short Name:
- COSMOSVLBA
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results of a project using wide-field Very Long Baseline Interferometry (VLBI) observations at 1.4 GHz of 2,865 known radio sources in the Cosmic Evolution Survey (COSMOS) field, a field which has exceptional multi-wavelength coverage. The main objective of this study is to identify the active galactic nuclei (AGN) in this field. Wide-field VLBI observations were made of all known radio sources in the COSMOS field at 1.4 GHz using the Very Long Baseline Array (VLBA). The authors also collected complementary multiwavelength information from the literature for the VLBA-detected sources.The combination of the number of sources, sensitivity, angular resolution and the area covered by this project are unprecedented. A catalog which contains the VLBI-detected sources is presented, the main purpose of which is to be used as an AGN catalog. the complementary multiwavelength (optical, infrared and X-ray) information of the VLBI-detected sources is also presented. The authors have detected 468 radio sources, expected to be AGN, with the VLBA. This is, to date, the largest sample assembled of VLBI-detected sources in the sub-mJy regime. They find a detection fraction of 20% +/- 1%, considering only those sources from the input catalog which were in principle detectable with the VLBA (2,361). As a function of the VLA flux density, the detection fraction is higher for higher flux densities, since at high flux densities a source could be detected even if the VLBI core accounts for a small percentage of the total flux density. As a function of redshift, the authors see no evolution of the detection fraction over the redshift range 0.5 < z < 3. In addition, they find that faint radio sources typically have a greater fraction of their radio luminosity in a compact core: ~70% of the sub-mJy sources detected with the VLBA have more than half of their total radio luminosity in a VLBI-scale component, whereas this is true for only ~30% of the sources that are brighter than 10 mJy. This suggests that fainter radio sources differ intrinsically from brighter ones. Across the entire sample, the authors find the predominant morphological classification of the host galaxies of the VLBA-detected sources to be early type (57%), although this varies with redshift and at z > 1.5 they find that spiral galaxies become the most prevalent (48%). The number of detections is high enough to study the faint radio population with statistically significant numbers. The authors demonstrate that wide-field VLBI observations, together with new calibration methods such as multi-source self-calibration and mosaicking, result in information which is difficult or impossible to obtain otherwise. This table contains 504 entries, including the 468 VLBA-detected sources and, for sources with multiple components, entries for the individual components. Among the detected sources, there are 452 single, 13 double, 2 triple and 1 quadruple source. Source entries have no suffix in their vlba_source_id, e.g., 'C3293', whereas component entries have a, b, c or d suffixes, e.g., 'C0090a' (and a value of 2 for the multi_cpt_flag parameter). This table was created by the HEASARC in December 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/607/A132">CDS Catalog J/A+A/607/A132</a> files vlba_cat.dat and vlba_mw.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/twodfqsoz
- Title:
- 2dF QSO Redshift (2QZ) Survey
- Short Name:
- TWODFQSOZ
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The final catalog of the 2dF QSO Redshift Survey (2QZ) is based on Anglo-Australian Telescope 2dF spectroscopic observations of 44,576 color-selected (u, b<sub>J</sub>, r) objects with 18.25 < b<sub>J</sub> < 20.85 selected from automated plate measurement scans of UK Schmidt Telescope (UKST) photographic plates. The 2QZ comprises 23,338 quasi-stellar objects (QSOs), 12,292 galactic stars (including 2,071 white dwarfs) and 4,558 compact narrow emission-line galaxies. The authors obtained a reliable spectroscopic identification for 86 per cent of objects observed with 2dF. They also report on the 6dF QSO Redshift Survey (6QZ), based on UKST 6dF observations of 1,564 brighter (16 < b<sub>J</sub> < 18.25) sources selected from the same photographic input catalog. In total, the authors identified 322 QSOs spectroscopically in the 6QZ. The completed 2QZ is, by more than a factor of 50, the largest homogeneous QSO catalog ever constructed at these faint limits (b<sub>J</sub> < 20.85) and high QSO surface densities (35 QSOs/deg<sup>2</sup>). As such, it represents an important resource in the study of the Universe at moderate-to-high redshifts. The survey area comprised 30 UKST fields, arranged in two 75 degrees by 5 degrees declination strips, one passing across the South Galactic Gap centered on Dec = -30 degrees (the SGP strip), and the other across the North Galactic Gap centered on Dec = 0 degrees (referred to in the reference paper as the equatorial strip, but also known as the NGP strip. The total survey area is 721.6 deg<sup>2</sup>, when allowance is made for regions of sky excised around bright stars. Spectroscopic observations of the input catalogue were made with the 2dF instrument at the Anglo-Australian Telescope (AAT; the 2QZ sample) and the 6dF instrument at the UKST (the 6QZ sample). 2dF spectroscopic observations began in January 1997 and were completed in April 2002. Six-degree Field observations were performed over the period 2001 March-2002 September. This online catalog was created by the HEASARC in October 2010 based on the machine-readable table 2qz.dat obtained from the CDS (their catalog VII/241). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/glxsdssqs2
- Title:
- GALEX/SDSS z=0.5-1.5 QSO Candidates Catalog
- Short Name:
- GLXSDSSQS2
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- A sample of ~60,000 objects from the combined Sloan Digital Sky Survey-Galaxy Evolution Explorer (SDSS-GALEX) database with UV-optical colors that should isolate QSOs in the redshift range 0.5 to 1.5 is discussed. The authors use SDSS spectra of a subsample of ~ 4,500 to remove stellar and galaxy contaminants in the sample to a very high level, based on the 7-band photometry. In their paper, they discuss the distributions of redshift, luminosity, and reddening of the 19,100 QSOs (~96%) that they estimate to be present in their final sample of 19,812 point sources. This latter catalog is available in the present table. This paper is based on archival data from the Galaxy Evolution Explorer (GALEX) which is operated for NASA by the California Institute of Technology under NASA contract NAS5-98034, and on data from the SDSS. This table was created by the HEASARC in March 2011 based on the electronic version of Table 2 from the reference paper which was obtained from the AJ web site. Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gcscat
- Title:
- Globular Cluster Systems of Galaxies Catalog
- Short Name:
- GCSCAT
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a catalog of 422 galaxies with published measurements of their globular cluster (GC) populations. Of these, 248 are E galaxies, 93 are S0 galaxies, and 81 are spirals or irregulars. Among various correlations of the total number of GCs with other global galaxy properties, the authors find that the number of globular clusters N<sub>GC</sub> correlates well though nonlinearly with the dynamical mass of the galaxy bulge M<sub>dyn</sub> = 4 sigma _e_<sup>2</sup> R<sub>e</sub>/G, where sigma<sub>e</sub> is the central velocity dispersion and R<sub>e</sub> the effective radius of the galaxy light profile. In their paper, the authors also present updated versions of the GC specific frequency S<sub>N</sub> and specific mass S<sub>M</sub> versus host galaxy luminosity and baryonic mass. These graphs exhibit the previously known U-shape: highest S<sub>N</sub> or S<sub>M</sub> values occur for either dwarfs or supergiants, but in the mid-range of galaxy size (10<sup>9</sup> - 10<sup>10</sup> L<sub>sun</sub>) the GC numbers fall along a well-defined baseline value of S<sub>N</sub> ~= 1 or S<sub>M</sub> = 0.1, similar among all galaxy types. Along with other recent discussions, the authors suggest that this trend may represent the effects of feedback, which systematically inhibited early star formation at either very low or very high galaxy mass, but which had its minimum effect for intermediate masses. Their results strongly reinforce recent proposals that GC formation efficiency appears to be most nearly proportional to the galaxy halo mass M<sub>halo</sub>. The mean "absolute" efficiency ratio for GC formation that the authors derive from the catalog data is M<sub>GCS</sub>/M<sub>halo</sub> = 6 x 10<sup>-5</sup>. They suggest that the galaxy-to-galaxy scatter around this mean value may arise in part because of differences in the relative timing of GC formation versus field-star formation. Finally, they find that an excellent empirical predictor of total GC population for galaxies of all luminosities is N<sub>GC</sub> ~ (R<sub>e</sub> sigma<sub>e</sub>)<sup>1.3</sup>, a result consistent with fundamental plane scaling relations. This table was created by the HEASARC in February 2014 based on an electronic version of Table 1 from the reference paper which was obtained from the ApJ web site. A duplicate entry for NGC 4417 was removed in June 2019. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/iraspscz
- Title:
- IRAS Point Source Catalog Redshift (PSCz) Catalog
- Short Name:
- IRASPSCZ
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The IRAS Point Source Catalog Redshift (PSCz) Survey consists of redshifts, infrared and optical photometry, and assorted other information for 18351 IRAS sources, mostly selected from the Point Source Catalog. The survey was designed to select almost all galaxies with flux brighter than 0.595 Jy at 60 microns (µm), over the 84% of the sky with extinction small enough that reliable and complete optical identification and spectroscopy was possible. Some of the sources are not galaxies and some are multiple entries for the same galaxy as described in the reference paper. There are in total 15,411 galaxies or possible galaxies, for which redshifts are available for 14,677. The galaxies without redshift are mostly distant or at low latitude, as described in the paper. Many of these galaxies have now been observed as part of the BTP project (Saunders et al 1999, astro-ph/9909174 "The Behind the Plane Survey"), and their redshifts were to be included in future revisions of this catalog. The full catalog for the PSCz Catalog contains more than 120 parameters and is available at the CDS in the directory <a href="http://cdsarc.u-strasbg.fr/ftp/cats/VII/221/">http://cdsarc.u-strasbg.fr/ftp/cats/VII/221/</a> as the files pscz.dat (18,351 sources in the main catalog) and psczcg.dat (60 additional sources close to the coverage gap). There is also a 'short' version of the catalog, psczvs.dat and psczcgvs.dat, containing 19 parameters, sufficient information for most studies. They correspond to the version 2.2. Many fields are taken directly from the IRAS Point Source Catalogue (CDS Cat. II/125). See the IRAS Explanatory Supplement (Beichman et al., 1988, NASAR, 1190, 1) for more information. If there are problems that cannot be resolved by careful reading of these notes or the accompanying paper, please contact Will Saunders <will@roe.ac.uk> or Will Sutherland <W.Sutherland1@physics.ox.ac.uk>. This table was created by the HEASARC in February 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/221">CDS Catalog VII/221</a> files psczvs.dat (the 'Main' sample) and psczcgvs.dat (the 'Near-gap' sample), comprising the 'Short' version of the PSCz Catalog. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/lqac
- Title:
- Large Quasar Astrometric Catalog, 3rd Release
- Short Name:
- LQAC
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Since the release of the original Large Quasar Astrometric Catalog (LQAC: Souchay et al. 2009, A&A, 494, 815), a large number of quasars have been discovered through very dense observational surveys. Following the same procedure as in the first release of the LQAC, the authors aim is to compile all the quasars recorded up until the present date, with the best determination of their ICRS equatorial coordinates, i.e., with respect to the newly established ICRF2 (the second realization of the International Celestial Reference Frame) and with the maximum of information concerning their physical properties, e.g., redshifts, photometry, absolute magnitudes. In the second paper, the authors first of all made a substantial review of the definitions and properties of quasars and AGN (Active Galactic Nuclei), the differentiation of these objects being unclear in the literature and even for specialists. This served their purpose when deciding which kinds of objects would be taken into account in this compilation. Then, they carried out the cross-identification between the 9 catalogs of quasars chosen for their accuracy and their huge number of objects, using a flag for each of them, and including all the available data related to magnitudes (infrared and optical), radio fluxes and redshifts. They also performed cross identification with external catalogs 2MASS, B1.0 and GSC2.3 in order to complete photometric data for the objects. Moreover, they computed the absolute magnitude of their extragalactic objects by taking into account recent studies concerning Galactic absorption. In addition, substantial improvements were brought with respect to the first release of the LQAC. First, an LQAC name was given for each object based on its equatorial coordinates with respect to the ICRS, following a procedure which creates no ambiguity for identification. Secondly, the equatorial coordinates of the objects were recomputed more accurately according to the algorithms used for the elaboration of the Large Quasar Reference Frame (LQRF) (Andrei et al., 2009, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/313">CDS Cat. I/313</a>). Thirdly, the authors introduced a morphological classification for the objects which enabled them in particular to define clearly if the object is point-like or extended. The authors adopted a cosmology with H<sub>0</sub> = 70 km s<sup>-1</sup> Mpc<sup>-1</sup>, Omega<sub>M</sub> = 0.3, Omega<sub>Lambda</sub> = 0.7, and q<sub>0</sub> = -0.65 in LQAC-3 (which is slightly different from that adopted for LQAC-2, notice). The final catalog, called LQAC-2, contained 187,504 quasars. This was roughly 65% larger than the 113,666 quasars recorded in the first version of the LQAC (Souchay et al. 2009, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/494/799">CDS Cat. J/A+A/494/799</a>) and a little more than the number of quasars recorded in the up-dated version of the Veron-Cetty and Veron (2010, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/258">CDS Cat. VII/258</a>, HEASARC VERONCAT table) catalog, which was the densest compilation of quasars up to the present one. In addition to the quantitative and qualitative improvements implemented in this compilation, the authors discussed the homogeneity of the data and carried out a statistical analysis concerning the spatial density and the distance to the nearest neighbor in their published paper. The authors adopted a cosmology with H<sub>0</sub> = 72 km s<sup>-1</sup> Mpc<sup>-1</sup> and q<sub>0</sub> = -0.58 in this study. From an astrometric point of view, quasars constitute quasi-ideal reference objects in the celestial sphere, with an a priori absence of proper motion. Since the second release of the LQAC, a large number of quasars have been discovered, in particular with the upcoming new release of the SDSS quasars catalog. Following the same procedure as in the two previous releases of the LQAC, The authors' aim for LQAC-3 was to compile all the quasars recorded until the present date, with accurate recomputation of their equatorial coordinates in the ICRS and with the maximum of information concerning their physical properties, such as the redshift, the photometry, and the absolute magnitudes. The authors carried out the cross-identification between the 9 catalogs of quasars chosen for their huge number of objects, including all the available data related to magnitudes, radio fluxes, and redshifts. This cross identification was particularly delicate because of a slight change in coordinates between the objects common to two successive releases of the SDSS and the elimination of some of them. Equatorial coordinates were recomputed more accurately according to the algorithms used for the elaboration of the Large Quasar Reference Frame (LQRF). Moreover, absolute magnitudes and morphological indexes of the new objects were given, following the same method as in the LQAC-2. The final catalog, called LQAC-3, contains 321,957 objects including a small proportion of AGNs (14,128) and BL Lac objects (1,183). This is roughly 70% more than the number of objects recorded in the LQAC-2. The LQAC-3 will be useful for the astronomical community since it gives the most complete information available about the whole set of already recorded quasars, with emphasis on the precision and accuracy of their coordinates with respect to the ICRF2. This table was created by the HEASARC in June 2016 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/583/A75">CDS Catalog J/A+A/583/A75</a>, file lqac3.dat. This is a service provided by NASA HEASARC .
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