- ID:
- ivo://nasa.heasarc/hcggalaxy
- Title:
- Hickson Compact Groups of Galaxies (HCG) Individual Galaxies Data
- Short Name:
- Hickson(Gal)
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The HCGGALAXY database table is based on the Hickson Catalog of Compact Groups, and contains data on 463 galaxies in 100 compact groups of galaxies that were identified by a systematic search of the Palomar Observatory Sky Survey red prints. Each group contains four or more galaxies, has an estimated mean surface brightness brighter than 26.0 magnitude per arcsec<sup>2</sup> and satisfies an isolation criterion. Astrometry, photometry, and morphological types, derived from CCD images, are presented for the 463 galaxies. Radial velocities are given for 457 of the 463 galaxies: more than 84% of the galaxies measured have radial velocities that are within 1000 km/s of the group median velocity. Morphological information derived from either an isophotal analysis or from a visual inspection of images is given for 210 of the 463 galaxies. This database table essentially contains the information given in Table 2 of Hickson, P. et al. (1989, ApJS, 70, 687), Table 2 of Hickson, P. et al. (1992, ApJ, 399, 353), and Table 2 of Mendes de Oliveira, C. and Hickson, P. (1994, ApJ, 427, 684). Consequently, the information on the properties of the Hickson Compact Groups as units that is also given in some of these references, e.g., in Table 3 of Hickson, P. et al. (1992, ApJ, 399, 353), is not in the HCGGALXY database table; however, the latter data can be found in the related HEASARC database table HCG. This database table was created by the HEASARC in August, 1999, based on machine-readable tables obtained from the ADC/CDS data centers (<a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/213">CDS catalog VII/213</a>, files galaxies.dat and morpho.dat). The HEASARC added Galactic coordinates and updated the table's metadata in August, 2005. This is a service provided by NASA HEASARC .
Number of results to display per page
Search Results
- ID:
- ivo://nasa.heasarc/intibisag2
- Title:
- INTEGRAL IBIS AGN Catalog Update
- Short Name:
- INTIBISAG2
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- In the most recent IBIS survey based on observations performed during the first 1000 orbits of INTEGRAL, there are listed 363 high-energy emitters firmly associated with AGN, 107 of which are reported here for the first time. The authors have used X-ray data to image the IBIS 90% error circle of all the AGN in the sample of 107, in order to obtain the correct X-ray counterparts, locate them with arcsecond accuracy and therefore pinpoint the correct optical counterparts. This procedure has led to the optical and spectral characterization of the entire sample. This new set consists of 34 broad line or type 1 AGN, 47 narrow line or type 2 AGN, 18 blazars and 8 sources of unknown class. These eight sources have been associated with AGN from their positional coincidence with 2MASX/Radio/X-ray sources. Seven high-energy emitters have also been included since they are considered to be good AGN candidates. Spectral analysis has been already performed on 55 objects and the results from the most recent and/or best statistical measurements have been collected. For the remaining 52 sources, the authors report the spectral analysis for the first time in this work. They have been able to obtain full X-ray coverage of the sample making use of data from Swift/XRT, XMM-Newton and NuSTAR. In addition to the spectral characterization of the entire sample, this analysis has enabled the authors to identify peculiar sources and by comparing different data sets, highlight flux variability in the 2-10 keV and 20-40 keV bands. In the reference paper, the authors present the X-ray and optical follow-up work on 107 new AGN recently detected by INTEGRAL. Fortunately, they have been able to obtain full X-ray coverage of the entire sample making use of data from the Swift/XRT, Newton-XMM, and NuSTAR archives or through Swift/XRT follow-up observations that they triggered. The HEASARC notes that this table of AGN newly detected by INTEGRAL and not included in the original INTEGRAL IBIS AGN Catalog (Malizia et al. 2012, MNRAS, 426, 1750, available at the HEASARC as the INTIBISAGN table) actually contains 108 AGN plus 8 candidate AGN, for a total of 116 objects, rather than the 107 plus 7 candidate AGN totalling 114 objects that are quoted in the abstract of the reference paper (and stated above). The reason for this discrepancy is not known to the HEASARC. This table was created by the HEASARC in November 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/460/19">CDS Catalog J/MNRAS/460/19</a> files tablea1.dat and refs.dat. 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:
- 02 May 2025
- 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/lbqs
- Title:
- Large Bright Quasar Survey
- Short Name:
- LBQS
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Positions, redshifts, and magnitudes for the 1055 quasars in the Large Bright Quasar Survey (LBQS) are presented in a single catalog. Celestial positions have been rederived using the PPM catalog to provide an improved reference frame. Redshifts calculated via cross correlation with a high signal-to-noise ratio composite quasar spectrum are included and the small number of typographic and redshift misidentifications in the discovery papers are corrected. Compared to the discovery papers (references below), 12 quasars that are either fainter than the field magnitude limit or fall outside the final survey area have been deleted, 12 quasars that were discovered subsequent to paper V have been added, 10 redshifts have been corrected, and 13 quasars with either incorrect or degenerate designations (LBQS names) have had their designations corrected. The information in this version of the LBQS Catalog is the same as in Table 4 of the published paper with the following exceptions: (i) the object 0021-0213 has a redshift of 2.348; this value was listed in Table 5 of the paper but was not incorporated in Table 4 of the paper; (ii) the parameter 'Reference' in Table 4 of the published paper (which specified in which paper in the LBQS series the quasar spectrum could be found) has been omitted; and (iii) the parameter 'Notes' in Table 4 of the published paper had two non-blank values: '+' and 'a'; in the HEASARC representation of this catalog we have replaced the Notes value of '+' by 'C', and dropped the Notes value of 'a' (used to indicate objects that had been listed as AGN in earlier papers). This catalog was created by the HEASARC in July 1999 based on a table that was kindly provided by the first author, Paul Hewett, supplemented by documentation created by the CDS/ADC. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/lqac
- Title:
- Large Quasar Astrometric Catalog, 3rd Release
- Short Name:
- LQAC
- Date:
- 02 May 2025
- 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 .
- ID:
- ivo://nasa.heasarc/lcrscat
- Title:
- Las Campanas Redshift Survey Catalog
- Short Name:
- LCRSCAT
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Las Campanas Redshift Survey (LCRS) consists of 26,418 redshifts of galaxies selected from a CCD-based catalog obtained in the R band. The survey covers over 700 deg<sup>2</sup> in six strips, each 1.5 x 80 degrees, three each in the north and south Galactic caps. The median redshift in the survey is about 30,000 km s<sup>-1</sup>. Essential features of the galaxy selection and redshift measurement methods are described and tabulated in the reference paper. These details are important for subsequent analysis of the LCRS data. Two-dimensional representations of the redshift distributions reveal many repetitions of voids, on the scale of about 5000 km s<sup>-1</sup>, sharply bounded by large walls of galaxies as seen in nearby surveys. Statistical investigations of the mean galaxy properties and of clustering on the large scale are reported elsewhere. These include studies of the luminosity function, power spectrum in two and three dimensions, correlation function, pairwise velocity distribution, identification of large-scale structures, and a group catalog. This table contains entries for 94959 objects from the LCRS for which photometric data were obtained and which were initially classified as galaxies on the basis of this photometric information, although subsequent spectroscopy indicated that a small fracton of them are actually stars. There are 27021 objects out of this total which have spectroscopic redshift information (either of themselves or of a nearby object). See also the LCRS home pages at: <a href="http://qold.astro.utoronto.ca/~lin/lcrs.html">http://qold.astro.utoronto.ca/~lin/lcrs.html</a>. This table was created by the HEASARC in May 2010 based on the electronic version of Table 3 from the above reference which was obtained from the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/203">CDS Catalog VII/203</a> file catalog.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/markarian2
- Title:
- Markarian Galaxies Optical Database
- Short Name:
- MARKARIAN2
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- A database for the entire Markarian (First Byurakan Spectral Sky Survey or FBS) Catalog is presented that combines extensive new measurements of their optical parameters with a literature and database search. The measurements were made using images extracted from the STScI Digitized Sky Survey (DSS) of F_pg (red) and J_pg (blue) band photographic sky survey plates obtained by the Palomar and UK Schmidt telescopes. The authors provide accurate coordinates, morphological type, spectral and activity classes, red and blue apparent magnitudes, apparent diameters, axial ratios, and position angles, as well as number counts of neighboring objects in a circle of radius 50 kpc. Special attention was paid to the individual descriptions of the galaxies in the original Markarian lists, which clarified many cases of misidentifications of the objects, particularly among interacting systems, larger galaxies with knots of star formation, possible stars, and cases of stars projected on galaxies. The total number of individual Markarian objects in the database is now 1544. The authors also have included redshifts which are now available for 1524 of the objectswith UV-excess radiation, as well as Galactic color excess E(B-V) values and their 2MASS or DENIS infrared magnitudes. The table also includes extensive notes that summarize information about the membership of Markarian galaxies in different systems of galaxies and about new and revised activity classes and redshifts. The new optical information on Markarian galaxies was obtained from images extracted from the STScI Digitized Sky Survey (DSS) of F_pg (red) and J_pg (blue) band photographic sky survey plates obtained by the Palomar and UK Schmidt telescopes. This table was created by the HEASARC in November 2009 based on the electronic version of the optical database of Markarian galaxies which was obtained from the CDS (their catalog J/ApJS/170/33 file table1.dat). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/twomassrsc
- Title:
- 2MASS Redshift Survey (2MRS) Catalog
- Short Name:
- TWOMASSRSC
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table is based on the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby universe. The Two Micron All Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available online. The 2MASS XSC contains nearly a million galaxies with K<sub>s</sub> <= 13.5 mag and is essentially complete and mostly unaffected by interstellar extinction and stellar confusion down to a galactic latitude of |b| = 5 degrees for bright galaxies. Near-infrared wavelengths are sensitive to the old stellar populations that dominate galaxy masses, making 2MASS an excellent starting point to study the distribution of matter in the nearby universe. The authors selected a sample of 44,599 2MASS galaxies with K<sub>s</sub> <= 11.75 mag and |b| >= 5 degrees (>= 8 degrees toward the Galactic bulge) as the input catalog for their survey. They obtained spectroscopic observations for 11,000 galaxies and used previously obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300 Mpc. Earlier versions of their survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 h<sup>-1</sup> Mpc, detected galaxy groups, and estimated the values of several cosmological parameters. Additionally, the authors present morphological types for a nearly complete sub-sample of 20,860 galaxies with K<sub>s</sub> <= 11.25 mag and |b| >= 10 degrees. The authors initially selected 45,086 sources which met the following criteria: <pre> K<sub>s</sub> <= 11.75 mag and detected at H, E(B - V) <= 1 mag, |b| >= 5 degrees for 30 degrees < l < 330 degrees, |b| >= 8 degrees otherwise. </pre> They rejected 324 sources of galactic origin (multiple stars, planetary nebulae, and H II regions) or pieces of galaxies detected as separate sources by the 2MASS pipeline. Additionally, they flagged 314 bona fide galaxies with compromised photometry for reprocessing at a future date. Some of these galaxies have bright stars very close to their nuclei which were not detected by the pipeline. Others are in regions of high stellar density and their center positions and/or isophotal radii have been incorrectly measured by the pipeline. Lastly, some are close pairs or multiples but the pipeline only identified a single object. A detailed explanation of the steps taken to reject and reprocess the flagged galaxies is given in the Appendix of the reference paper. In summary, the final input catalog contained here has 44,599 entries (plotted using black symbols in Figure 1 of the reference paper). In this table, redshifts for 43,533 of the selected galaxies, or 97.6% of the sample, are presented. This table was created by the HEASARC in April 2012 based on an electronic version of Table 3 of the reference paper which was obtained from the ApJS website. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/mcxc
- Title:
- MCXC Meta-Catalog of X-Ray Detected Clusters of Galaxies
- Short Name:
- MCXC
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The MCXC is the Meta-Catalog of the compiled properties of X-ray detected Clusters of galaxies. This very large catalog is based on publicly available ROSAT All Sky Survey (RASS)-based (NORAS, REFLEX, BCS, SGP, NEP, MACS, and CIZA) and ROSAT serendipitous (160SD, 400SD, SHARC, WARPS, and EMSS) cluster catalogs. Data have been systematically homogenised to an overdensity of 500, and duplicate entries from overlaps between the survey areas of the individual input catalogs have been carefully handled. The MCXC comprises 1743 clusters with virtually no duplicate entries. For each cluster, the MCXC provides three identifiers, a redshift, coordinates, membership in the original catalog, and standardised 0.1 - 2.4 keV band luminosity Lx<sub>500</sub>, total mass M<sub>500</sub>, and radius R<sub>500</sub>, where the 500 suffix means that the quantity has been calculated up to a standard characteristic radius R<sub>500</sub>, the radius within which the mean overdensity of the cluster is 500 times the critical density at the cluster redshift . The meta-catalog additionally furnishes information on overlaps between the input catalogs and the luminosity ratios when measurements from different surveys are available, and gives notes on individual objects. The MCXC is made available so as to provide maximum usefulness for X-ray, Sunyaev-Zel'dovich (SZ) and other multiwavelength studies. The catalogs and sub-catalogs included in this meta-catalog are listed in Table 1 of the reference paper, and come from the following references: <pre> Catalog Sub- Reference Title Catalog or CDS Cat. (Author) RASS IX/10 ROSAT All-Sky Bright Source Catalog (1RXS) (Voges+, 1999) BCS BCS J/MNRAS/301/881 ROSAT brightest cluster sample - I. (Ebeling+, 1998) eBCS J/MNRAS/318/333 Extended ROSAT Bright Cluster Sample (Ebeling+ 2000) CIZA X-ray clusters behind the Milky Way CIZAI ApJ, 580, 774 (Ebeling+, 2002) CIZAII J/APJ/662/224 (Kocevski+, 2007) EMSS ApJS, 72, 567 Einstein Extended Medium Sensitivity Survey (Gioia+, 1990) EMSS_1994 ApJS, 94, 583 (Gioia & Luppino, 1994) EMSS_2004 ApJ, 608, 603 (Henry 2004) MACS ApJ, 553, 668 Massive Cluster Survey (Ebeling+, 2001) MACS_MJFV ApJS, 174, 117 (Maughan+, 2008) MACS_BRIGHT MNRAS, 407, 83 (Ebeling+, 2010) MACS_DIST ApJ, 661, L33 (Ebeling+, 2007) NEP NEP J/ApJS/162/304 ROSAT NEP X-ray source catalog (Henry+, 2006) NORAS/ REFLEX NORAS J/ApJS/129/435 NORAS galaxy cluster survey. I. (Boehringer+, 2000) REFLEX J/A+A/425/367 REFLEX Galaxy Cluster Survey Cat (Boehringer+, 2004) SGP SGP J/ApJS/140/239 Clusters of galaxies around SGP (Cruddace+, 2002) SHARC SHARC_BRIGHT J/ApJS/126/209 Bright SHARC survey cluster catalog (Romer+, 2000) SHARC_SOUTH J/MNRAS/341/1093 The Southern SHARC catalog (Burke+, 2003) WARPS WARPSI J/ApJS/140/265 WARPS survey. VI. (Perlman+, 2002) WARPSII J/ApJS/176/374 WARPS-II Cluster catalog. VII. (Horner+, 2008) 160SD 160SD J/ApJ/594/154 160 square degree ROSAT Survey (Mullis+, 2003) 400SD J/ApJS/172/561 400 square degree ROSAT Cluster Survey (Burenin+, 2007) 400SD_SER Serendipitous clusters 400SD_NONSER Not entirely serendipitous clusters </pre> This table was originally ingested by the HEASARC in October 2011 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/534/A109">CDS catalog J/A+A/534/A109</a> file mcxc.dat. It was last updated in September 2023 to match the 12-Nov-2011 CDS version of the catalog. This update corrected the missing minus signs in the declinations of 6 clusters and homogenized the Abell object names. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/milliquas
- Title:
- Million Quasars Catalog (MILLIQUAS), Version 8 (2 August 2023)
- Short Name:
- MILLIQUAS
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Million Quasars (MILLIQUAS) Catalog, Version 8 (2 August 2023). It is a compendium of 907,144 type-I QSOs and AGN, largely complete from the literature to 30 June 2023. 66,026 QSO candidates are also included, calculated via radio/X-ray association (including double radio lobes) as being 99% likely to be quasars. Blazars and type-II objects are also included, bringing the total count to 1,021,800. 60.7% of all objects show Gaia-EDR3 astrometry. Low-confidence/quality or questionable objects (so deemed by their researchers) are not included in Milliquas. Additional quality cuts can be applied as detailed in the HMQ paper (Flesch 2015,PASA,32,10). Full QSO/AGN classification is accomplished via spectral lines, yielding a reliable spectroscopic redshift. Two spectral lines are required, or one spectral line refining a compatible photometric redshift. Obscured AGN with redshifts from the hosts only are taken to be type-II objects. Some legacy quasars with neither good spectra nor radio/X-ray association were flagged by Gaia-EDR3 as 5-sigma moving (i.e., stars), and so were removed from Milliquas. All objects are de-duplicated across source catalogs. The author's aim here is to present one unique reliable object per each data row. Two NIQs offset < 2 arcsec can be reported as a single object if within the same host. Lenses are reported as single objects onto the brightest quasar imaged. (Milliquas is not a catalog of lenses.) The contents are relatively simple; each object is shown as one entry with the sky coordinates (of whatever epoch), its original name, object class, red and blue optical magnitudes, PSF class, redshift, the citations for the name and redshift, and up to four radio/X-ray identifiers where applicable. Questions/comments/praise/complaints may be directed to Eric Flesch at eric@flesch.org. If you use this catalog in published research, the author requests that you please cite it. The confirmed quasars of this catalog (to Jan 2015) were published as the Half Million Quasars (HMQ) catalog: Flesch E., 2015,PASA,32,10. Note however that Milliquas uses optical sky data from ASP (2017,PASA,34,25) whereas the HMQ used optical sky data from QORG (2004,A&A,427,387) Appendix A. This table was updated by the HEASARC in July 2023 based on a machine-readable catalog obtained from the author's MILLIQUAS website at <a href="https://quasars.org/milliquas.htm">https://quasars.org/milliquas.htm</a>. <p> This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. <p> This research has made use of the SIMBAD database and CDS cross-match service (to obtain Gaia-EDR3 and Pan-STARRS photometry) provided by CDS, Strasbourg, France. <a href="https://simbad.cds.unistra.fr/simbad">https://simbad.cds.unistra.fr/simbad</a> This is a service provided by NASA HEASARC .
