MILLIQUAS - Million Quasars Catalog, Version 7.7 (15 October 2022)
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. Accordingly, obscured AGN for which the redshift is taken from the host may be absent from Milliquas. The author's aim here is to present one unique reliable object per each data row. All objects are de-duplicated across source catalogues. 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 source, although some extra images are identified (as type L) if they carry radio/X-ray associations. Milliquas is not a catalogue of lenses.
This version has the following changes from the previous edition:
(1) Quasars added from publications to 15 October 2022. (2) Some quasar candidates of pQSO 60%-79% were missing; now added. (3) Positional fixes done on ~6000 candidates which had "epoch 2000" astrometry from USNO-B. Where USNO-B adjudged the object to be moving, the epoch 2000 projection could be discrepant by many arcsec. Pan-STARRS astrometry has been obtained for these objects as available, i.e., those of decl>-30. Those remaining have been flagged as questionably located.
Note: The author readied Gaia-DR3 astrometry to replace DR2 in Milliquas, but testing found that DR2 has better completeness of desired objects in crowded sky. Examples are J121450.06-055228.1 and SDSS J222942.84+002954.0, both of which are close Red-blue doublets for which VLASS gives a radio detection onto the blue object; Gaia-DR2 presents those blue objects but Gaia-DR3 gives only the red. The author suggests that maybe a Gaia on-spacecraft software change has prioritized red/yellow sources over blue, but whatever the cause, the author has decided that Gaia-DR2 seems better suited.
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 email@example.com. If you use this catalog in published research, the author requests that you please cite it. The paper for Milliquas is at https://arxiv.org/abs/2105.12985. Please cite as Milliquas v7.7 (2022) update, Flesch, E.W. 2021,arXiv:2105.12985 or as the refereed citation, Milliquas v7.7 (2022) update, Flesch, E.W. 2015,PASA,32,10.
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 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.
This research has made use of the SIMBAD database and cross-match service (to obtain Gaia DR2 and Pan-STARRS data) provided by CDS, Strasbourg, France. https://simbad.u-strasbg.fr/simbad
Flesch, E. The Million Quasars (MILLIQUAS) Catalog, Version 7.7 (15 October 2022) https://quasars.org/milliquas.htmSee also:
APM Catalog http://www.ast.cam.ac.uk/~mike/apmcat USNO-A/B Catalogs http://tdc-www.harvard.edu/catalogs/ub1.html NVSS Catalog http://www.cv.nrao.edu/nvss FIRST Catalog http://sundog.stsci.edu SUMSS Catalog http://www.astrop.physics.usyd.edu.au/sumsscat/ MGPS Catalog http://www.astrop.physics.usyd.edu.au/mgpscat/ https://www.sydney.edu.au/science/our-research/research-centres/sydney-institute-for-astronomy/astronomy-surveys.html ROSAT Catalogs http://www2011.mpe.mpg.de/xray/wave/rosat/catalogue/index.php 1WGA Catalog https://heasarc.gsfc.nasa.gov/wgacat/ Chandra Source Catalog http://cxc.cfa.harvard.edu/csc/ XAssist Home Page https://asd.gsfc.nasa.gov/xassist/ XMM-Newton Catalog http://xmmssc.irap.omp.eu/ XMM-Newton Slew Survey http://www.star.le.ac.uk/~amr30/Slew
0.1 22Apr09 0.3 6May09 Added a radio identifier and an X-ray identifier. 0.5 11May09 Added 30816 objects from newly calculated associations to XMM, Chandra and SUMSS detections, plus some tweaks. Also added QSO probability % for non-confirmed QSOs. 0.8 22Jun09 Added Chandra Source Catalog 1.0 (2009). 1.0 3Aug09 Extensive de-duplication. XMM Slew Catalog data added. 1.4 20Aug09 Misc fixes in the de-duplications. 1.5 29Aug09 Used XMM Slew Catalog v1.3 2.0 14Jun10 Used XMM Slew Catalog v1.4, XMM3, and XAssist4. 2.1 17Aug10 Removed 8627 NELGs masquerading as AGNe. 2.2 7Jan11 About 10,000 AGNe from the previous edition are now presented as QSOs. 796 AGNe mistakenly expunged in 2.1 have been restored. 2.3 5Mar11 SDSS DR-8 and BOSS targets have been included and the threshold for inclusions of candidates has been raised from 60% to 70%. 2.4 5Jun11 Improved QSO-likelihood calculation for the BOSS targets, so 17% of previously included BOSS targets drop out. Newly included data from several sources (see above). 2.5 20Jul11 Some de-duplication of quasars which were discovered prior to 1990, 200 recent NED quasars added, some radio/X-ray associations to USNO-B optical data added. 2.6 10Sep11 The USNO-B catalog has been added and hard-deduplicated against APM and SDSS data to make a background pool of 1.04 billion optical objects. Also, about 12 million orphaned one-color APM objects have been removed. There are consequently improvements in this catalog's optical selections and astrometry without changing the net totals much. XMM Slew 1.5 catalog added. Some further astrometric fixes and de-duplications of early quasars. 2.7 5Nov11 New quasar publications to 4 November 2011 were added, and a few fixes on individual objects incorporated. 2.8 29Jan12 Completed the fixes of non-astrometric relic data from the Veron-Cetty & Veron 13th edition. About 150 other fixes. Quasars compilation updated through 27 January 2012. 2.9 2Apr12 Data brought up to publications as of 31 March 2012, about 50 astrometric fixes done, and the new FIRST radio catalog, 12Feb16 version, incorporated. 2.10 6Aug12 Data brought up to publications as of 31 July 2012, including the SDSS-DR9 release, XAssist XMM-Newton and Chandra X-ray data updated to 30 June 2012; as this is a catalog for type I (broad-line) objects, 1870 Seyfert-2s, 532 LINERs, and 6 NELGs were removed, but BL Lacs were retained as unconstrained emission objects. 3.0 9Sep12 Data brought up to publications as of 31 August 2012. Redshifts are calculated for the XDQSO photometric quasar candidates. Fixed issues with 30 DEEP2 object. Separated out 15 SDSS-DR9 object that had been conflated with others. QSO-AGN separator restored to that used through v2.9, thus ~5000 QSOs were re-classified as AGNe. AGNe historic names sourced from the Principal Galaxy Catalogue. 3.1 22Oct12 Quasar data brought up to publications as of 20 Oct. 2012, including the new DR9 Quasar catalog (Paris I., 2012, arXiv:1210.5166). 3.2 10Feb13 Quasar data brought up to publications as of 9 Feb. 2013. MMT quasar positions fixed, and made a few small miscellaneous fixes. 3.3 7Apr13 Quasar data brought up to publications as at 6 April 2013. Added 713 new quasars from Palanque-Delabrouille et al. (2013, A&A, 551, A29). Included SWIRE data, consisting of 117 confirmed quasars and >20K photometric quasars from Rowan-Robinson et al. (2013, MNRAS, 428, 1958). Located 8 QSOs that were previously uncertainly located and removed 1 that had no credible candidates. Removed 26 SDSS-DR9 quasars after inspection showed they were only artifacts. Removed 144 questionable quasars from Iovino et al. (1996, A&AS, 119, 265). Removed 8 blazars classified as white dwarfs by the SDSS DR7 WD Cat (2013,ApJS,204,5). Miscellaneous: 4 moves, 2 de-dups, and 4 deletions found after extensive trawling. 3.4 11Jul13 Quasar data brought up to publications as at 11 July 2013. The author's paper (2013, PASA, 30, 4) marked 9 QSOs as uncertainly located. Of those: (a) Q 0112-27 is finally sited at J011517.2-271223, courtesy Cyril Hazard. (b) Q 0752+617 is moved to J075646.6+613639, r=16.9, b=17.4, as a better fit with its co-published quasar (NOTNI 16, r=16.7, b=17.2). Added 92 new quasars from Cyril Hazard. Q 1409+732 was found to be sited on a plate flaw, and is now moved one arcmin due East to perfect optical fit at J141003.2+725939, r=19.3, b>22. XAssist v4 XMM-Newton & Chandra X-ray data updated to 30-June-2013. 3.5 11Aug13 Quasar data brought up to publications as at 10 August 2013, including SDSS-DR10. Note that the DR10 is an automated catalog, so its object classifications are not as trustworthy as manual classifications. Thus, earlier manual classifications are retained over DR10 classifications. XMM-Newton X-ray data updated to 3XMM-DR4 version (24-July-2013). FIRST radio data updated to 13Jun05 version (05-June-2013). 3.6 23Oct13 Quasar data brought up to publications as at 22 October 2013. Two additional columns of radio/X-ray detections were added. This is so that any radio lobes will always be fully displayed, and extra detections from other source catalogs give a sense of fuller coverage. 158 additional quasars were added from SDSS-DR10. These were flagged as bad astrometry, but they are confirmed by the author's optical background database. Photometric quasar candidates from surveys other than NBCKDE and XDQSO, e.g., SWIRE, have been dropped because much of their yield are type 2. This includes Palanque-Delabrouille et al. (2011,A&A,530,122), which has been well investigated spectroscopically and its residue thus less likely to be QSOs. X-ray detections from the Champ2 catalog, Kim M. et al., 2007,ApJS,169,401 have been removed. It's a small catalog which, unlike others, does not present its raw astrometry needed for calculating optical solutions. The Veron quasar catalog v13 (2010 A&A,518A,10) included some objects denoted as non-quasars by their discovery papers, and the following have been removed as a result: (a) 484 emission-line galaxies (ELGs) of z<0.46 from Schneider/Schmidt/Gunn 1994,AJ,107,1245, incorporated as QSOs by VCV13; (b) 55 ELGs of Schneider/Schmidt/Gunn 1999,AJ,117,40; (c) 58 galaxies from 2dF-GRS (Colless M. et al., astro-ph/0306581); and (d) 41 galaxies from La Franca F. et al., 1999,A&AS,140,351. A few positional fixes, de-duplications, and removals of type-2s. 3.7 26Nov13 Quasar data brought up to publications as at 26 November 2013, including the SDSS DR10Q release by Isabelle Paris et al., 2013 arXiv:1311.4870. 318 SDSS "quasars" of auto-redshift>4 which were not subsequently confirmed by visual inspection are removed as bogus (communication Adam Myers). The Veron quasar catalog v13 (2010 A&A,518A,10) flagged some objects as questionable in their "spec" field. These have unclear spectra or are described as "possible" by their discovery papers. 178 of these are removed, and 52 such BL Lacs with redshift>0.5 are re-classed to AGNs. Some positional fixes and de-duplications of individual objects. 3.8 16Feb14 Quasar data brought up to publications as at 15 February 2014. NBCKDE and BOSS quasar likelihoods have been calibrated against the DR10Q (Paris I. et al., 2013 arXiv:1311.4870) classifications. The Swift X-ray Point Source catalog (Evans P.A. et al., 2014,ApJS,210,8) is added to the background data, resulting in 12604 associations. 110 SDSS-DR10 automated survey objects are removed as artifacts. De-duplication of radio/X-ray detections improved. 3.9 30Jun14 Quasar data brought up to publications as at 30 June 2014. The XMM-Newton Slew Survey source catalog release 1.6 was added to X-ray data. The 1SXPS X-ray detections were being dropped; this was fixed and 21268 were included as a result. The Veron-Cetty & Veron Quasar Catalog (VCV) 13th edition (2010,A&A,518,10) was fully mapped into optical; corrections from this were incorporated. 4.0 05Aug14 Quasar data brought up to publications as at 5 August 2014. The threshold for inclusion of QSO candidates was raised to 80% confidence. This resulted in the loss of ~240,000 objects from v3.9, but it improved the confidence of use. XAssist v4 XMM-Newton and Chandra X-ray data was updated to 21-July-2014. 98 entries were found to be type II or not quasars, and so removed. The catalog layout was changed to conform better to the NED guide "Best Practices for Data Publication" by Marion Schmitz et al. (v1.2, 2013) in these ways: (a) all citations were changed to original discovery papers and no longer to VCV 13th edition or to NED and discovery citations are now indexed in a separate file; (b) quasar and radio/X-ray names which used to run together have been corrected to adhere to naming standards. 4.1 20Oct14 Quasar data brought up to publications as at 5 October 2014. The input values of RA and DEC used for this table were given in degrees rather than sexagesimal. Type 2 objects were included for the convenience of the users, but completeness of these is only about 95%. The type I objects are believed to be 100% complete from the literature. About 3000 SDSS "quasars" were removed as not quasars. These were auto-objects which were not taken up by the manual Paris files, and which were not given a subclass by the SDSS pipeline -- thus, the lowest quality objects. Another 2000 were reclassified as AGN or type 2 in this catalog. VCV mis-copied the redshifts from 2008 A&A,488,417 -- now fixed. QSOs & AGN re-partitioned by psf class and modified luminosity equation. Miscellaneous tweaks and fixes done when revealed by publication-related analysis. 4.2 06Dec14 Quasar data brought up to publications as at 6 December 2014. SDSS DR10/DR10Q and DR7/DR7Q data were reprocessed, yielding a few more quasars and using the DR10Q redshifts more as the current standard. Further adjustments were made to the luminosity equation separating QSOs from AGN, resulting in about 2000 AGN reclassified as QSOs. 18 new quasars from Dan Weedman, based on his re-analysis of the Weedman 1985 spectra in combination with NBCKDE photometric redshifts for those objects. 4.3 11Jan15 Quasar data brought up to publications as at 10 January 2015, including the newly-released SDSS-DR12 and SDSS-DR12Q (www.sdss.org). Approximately, 800 quasars sourced from the AGES catalog, Kochanek et al. (2012, ApJS, 200, 8). Approximately, 200 extra quasars added in a full round-up from NED and SIMBAD. 4.4 06Feb15 Quasar data brought up to publications as at 25 January 2015. Some reprocessing of the SDSS-DR12 and SDSS-DR12Q data. About 1000 type-1 objects reclassified to type-2. Photometric candidate likelihoods and redshifts were recalibrated using the SDSS-DR12Q quasars as the benchmark. 4.5 10May15 780 new quasars from LAMOST-DR1 (Luo et al. 2015, arXiv:1505.01570) were added. LAMOST-DR1 is a pipeline catalog with much provisional data, so the author selected the best-eligible objects only. LAMOST plans a manual (reliable) QSO catalog later this year. Also, NED/SIMBAD quasar data is included up to 9 May 2015. Citations were greatly simplified, referencing the recently published Half Million Quasars catalog (HMQ: Flesch E., 2015 PASA, 32, 10, arXiv:1502.06303) for smaller legacy citations while still citing large surveys like SDSS and 2QZ. A legend for the citations is given below, and the separate citations file is no longer needed as a result of this. 3XMM-DR5 (Rosen et al., 2015, arXiv:1504.07051) included in X-ray data. Also, high-confidence data from 2XMMi-DR3 is included, as acknowledged in section 8.2 of the Rosen paper (dropped 2XMMi-DR3 data recognized as valid). Minor fixes to optical data resulted in a few more radio/X-ray associations. 4.6 30Nov15 Additional QSO candidates were sourced from the new NBCKDE v3 catalog (Richards G.T. et al., 2015-ApJS-219-39) and a variability and refraction sourced catalog (Peters C.M. et al., 2015-ApJ-811-95). These added about 300,000 new candidates to Milliquas. Note that the NBCKDE v3 catalog uses different selection criteria from its predecessor, and so augments it rather than superseding it. The threshold for inclusion of QSO candidates was raised from 80% QSO-likelihood to 90%, so the catalog should be reliable even for spot checks. NED and SIMBAD listed quasars were included through 30-Nov-2015. 4.7 02Mar16 527 new QSOs were added from recent publications, including 33 new QSOs with z>5 of which 4 have z>6. The UV-Bright Quasar Survey (UVQS, T.R. Monroe et al., arXiv:1602.06255) was included with two mag-14 and 43 mag-15 QSOs plus many brighter AGN. 4.8 22Jun16 The Chandra ACIS source catalog (Wang S. et al., 2016,ApJS, 224,40) was added and new X-ray associations calculated. The 2nd RASS source catalog 2RXS (Boller Th. et al., 2016, A&A,588,103) replaced 1RXS for the most part, with significant differences in places. Radio/X-ray processing was tightened and data recalibrated to improve likelihood reliability, as part of a new radio/X-ray catalog in preparation. 23,727 radio/X-ray associated objects, recently dropped, were restored on the criterion that they are each 80%+ likely to be true quasars. This was done because this information is not found elsewhere. 4.8b 30Jul16 The 3XMM-DR6 X-ray source catalog was added and new X-ray associations calculated. The radio/X-ray data have been reprocessed in line with that of the Million Optical Radio/X-ray (MORX) Associations Catalog (Flesch 2016, PASA, 33, 52). 5.0 19Jun17 The J2000 coordinates now have 1/10th arcsecond precision, and the magnitudes have 1/100th mag precision, either from the original surveys or from the All-Sky Portable (ASP) optical catalog (arXiv:1705.05434). 5414 net QSOs/AGNs were added from recent surveys (listed below), notably AAOz, OzDES, LAMOST DR2, and a reload of AGES. The 3XMM-DR7 and XMMSL2-2.0 Slew X-ray source catalogs were added and new X-ray associations calculated. A few duplicates were removed. Notably, SDSS J131715.46+601533.1 was found to be a duplicate of SBS 1315+605. 5.1 30Jun17 Included full coverage of the Subaru-XMM Deep Field from multiple authors, LAMOST DR3, and other miscellaneous papers. 5.2 05Aug17 SDSS-DR14 and SDSS-DR14Q were added, using the processing rules from the Half Million Quasars catalog (HMQ: Flesch 2015, PASA, 32, 10). WISE quasar candidates were added from Secrest et al. 2015, ApJS, 221, 12. These are ~430,000 candidates over the whole sky for which 2-color optical objects were found within a 2-arcsec radius. They were processed into pQSOs from calibration against the SDSS-DR12Q multi-class superset, and photometric redshifts obtained using the four-color based method from the HMQ Appendix 2. The four colors used were B-R, R-W1, W1-W2, and W2-W3. Type-II narrow emission-line galaxies (NELGs, class='N') were added as the luminosity class corresponding to the type-I AGN galaxies. High-luminosity type-II NLAGN (class='K') correspond to the type-I quasars. The NLAGN/NELG divider is the same luminosity/psf function which separates QSOs from AGNs. Type-II NELGs include unquantified contamination by LINERs and probably a few starbursts which eluded removal, so it serves as a catch-all category presented for completeness, rather than as a strict type-II class. Small publications through 5 August 2017 were added. Positional fixes (of about 2 arcsec) were applied to ~150 objects. 5.3 12Sep18 Radio/X-ray association likelihoods calculated to a granularity of 1/10th of an arcsecond for Chandra, XMM-Newton, and Swift X-ray source catalogs and the FIRST radio source catalog. All associations have been recalculated onto the APM/USNO-B optical background of Flesch 2017,PASA,34,25 (Figure 3). Radio/X-ray association likelihoods to faint SDSS sources not in the optical background were previously halved, based on the approximately doubled sky density of SDSS. This deduction was changed to be classed by PSF and red-blue color, consequentially most SDSS likelihoods were reduced more, often by 60%-90%. Associations to other faint objects were also reduced. The overall effect was that ~20,000 candidates fell below the 80% likelihood threshold for inclusion in Milliquas, and so were removed. Visually inspected quasars from the LAMOST DR3Q (Dong et al., 2018,AJ,155,189) and auto-quasars from the LAMOST DR4 (https://dr4.lamost.org/) were quality checked and a total of 10,624 quasars/AGN added to Milliquas. 5.4 17Oct18 Quasars from individual papers from August 2017 forward to 15 October 2018 have been added, plus some from a couple older papers. Quasar doublets are more carefully processed to show 2 quasars instead of 1. A few gravitationally lensed images are added as type='L', in addition to the already-catalogued brightest one. These are added only where the optical data shows them in order to account for any radio/X-ray associations to them. The 3XMM-DR8 X-ray source catalog has been added and new X-ray associations calculated. A bug in v5.3 dropped radio/X-ray associations to some high-z quasars was fixed. 5.5 19Nov18 Quasars from publications to 14 November 2018 were added. The SDSS data were reprocessed to ensure DR14 data is used where available. Close quasar pairs and lens images processing was completed. 631 "unknown class" (type=U) objects (SDSS pipeline QSOs without subclass) were added. There are not usually accepted into Milliquas but they had probable radio/X-ray associations of p>80% which thus qualify them for inclusion. The SDSS pipeline redshift for these were included provisionally. The J2000 decimal round-up was increased to avert truncation. 5.6 17Dec18 Quasars from publications to 15 December 2018 were added. The 3rd release of SDSS-DR14Q (v4.4) was incorporated, adding ~300 quasars which had no astrometry in their earlier releases. All SDSS data was reprocessed to get rid of artifacts which had crept in. In preparation for LAMOST DR5Q (Yao et al 2018,arXiv:1811.01570), the LAMOST DR4 auto-quasars were demoted to quasar-candidates. LAMOST pipeline quasars were processed using the same rules as with SDSS pipeline. Removed 223 objects from Iovino/Clowes/Shaver,1996,A&AS,119,265 which had no quasar profile nor radio/X-ray/WISE associations, leaving 917 in Milliquas, resolving the cautionary note from HMQ (2015,PASA,32,10) section 2.B.4 end. 5.7 07Jan19 Quasars were added from publications to 7 January 2019, including LAMOST QSO DR5. The logic was tightened up for using SDSS SUBCLASS and ZWARNING fields to decide classifications for SDSS objects, including pipeline-only candidates. Milliquas was previously classifying all QSOs/AGN of z<0.1 as AGN. This boundary was moved to z=0.05 because of many core-dominated QSOs between z=0.05 and 0.1, e.g., IRAS 01267-2157 (SDSS J012910.99-214156.8) at z=0.93. HMQ (2015,PASA,32,10), section 5, discusses these luminosity-based boundaries. 22 objects from Boyle et al., 1990,MNRAS,243,18, classified by them as "possible" QSOs with "uncertain" redshifts, were removed from Milliquas. Positional fixes were done on ~90 legacy objects, mostly moves of <5 arcsec. 6.0 15Mar19 Quasars were added from publications to 15 March 2019. For ease of use, the "HMQ" citation (necessitating consultation of the HMQ catalog 2015-PASA-32-10 to identify the discovery article) was replaced by the HMQ-given 4-digit citation number. 30512 entries were changed, and the HMQ references file can be directly consulted for any numeric citation, making Milliquas into a stand-alone catalog. Positional fixes were made to 9 legacy objects. Where SDSS had a different redshift for a LAMOST-discovered quasar, if the difference is >0.1z, the name and discovery credit were transferred to SDSS. This was done for 6 objects. 42 AGN are dropped because their discovery paper Mauch & Sadler 2007,MNRAS,375,931 flagged those classifications as "not certain" and they had neither stellar psfs nor secure (80%+) radio/X-ray associations. The unseen Soviet BAL quasar "SBS 1401+566" was dropped. The quasar "Q 1409+732" was moved to the coordinates stated by its discovery paper Anderson & Margon 1987,Nature,327,125, where a suitable object resides. Confusion came from that paper's discrepant finding chart onto a plate flaw. 6.1 12May19 Quasars were added from publications to 12 May 2019. Gaia-DR2 astrometry was used and flagged for 63% of Milliquas (MQ) objects. Gaia sources were matched 1-to-1 with MQ objects on the criterion that the Gaia source is that nearest to the MQ object and that the MQ object is that nearest optical (out of a 1.163G optical DB) to the Gaia source. Care was taken to avoid false matches. 99% of all matches are within an arcsec offset, but to find valid farther matches, all matches were binned by object class and offset distance in 0.1 arcsec bins, with hundreds of targeted spot checks done to refine offset limits and to check objects with anomalous Gaia BP-RP color suggestive of a false match. SDSS quasar candidates could not be matched beyond 1 arcsec offset because they are often optically faint and/or in close groups for which Gaia had a different object only. AGN cores match to 1.5 arcsec beyond which Gaia often shows nearby stars only. QSOs/Bl-Lacs match well out to within 4 arcsec; for these I spot-checked all matches beyond 2 arcsec and all with off-colors beyond 1 arcsec offset and removed 14 false matches. However, for Gaia sources without BP and RP colors, QSOs match reliably only within 2 arcsec and Bl-Lacs within 1.5 arcsec. X-ray/radio-only candidates (unique to MQ) match reliably out to within 2.5 arcsec offset. In all cases it was paramount to avoid false matches, thus very many true matches were lost beyond the offset cutoffs. Reclassifications were done for Milliquas objects deemed by the SDSS-DR14 pipeline to be plain galaxies -- these were heavily spot-checked to confirm. 16 QSOs, 172 AGN and 2343 type-II objects were found to be just galaxies and so are dropped, and 433 host-dominated QSOs were reclassified to AGN. 6.2 22May19 About 50 fixes were done on Gaia-DR2 opticals selected in crowded places. Quasars were added from publications to 22 May 2019, including the PS-ELQS. 3LAC was reprocessed to fix a few selections and improve completeness. The z=2.136 QSO "SDSS J101012.77+560520.0", overlooked by SDSS, was added. 6.3 16Jun19 Quasars were added from publications to 15 June 2019, including 4LAC. 3,581 galaxies with double radio lobes were added as type=G because the lobes show that they have active nuclei of some kind, even if well hidden. Positional fixes of a few arcsec were done for ~50 legacy objects. Blazar candidates with neither redshift nor radio/X-ray association, about 30 objects, were dropped. Most were stated to be low confidence in legacy papers. 6.4 11Dec19 Quasars were added from publications to 11 December 2019. The SDSS-DR16 pipeline release was added. The author processed it using the standard HMQ rules which yield QSO classifications that accord well to the follow-up manual SDSS classifications. A new rule for Milliquas classification was added such that STARFORMING and STARBURST subclasses, or GALAXY classification by the DR12Q superset, are now taken to indicate optical host domination, e.g., classed as AGN instead of QSO. More candidates with double radio lobes were added, active nuclei being indicated. A photometric threshold guards against starforming interlopers. The pQSOs of SDSS candidates which are eBOSS targets were lowered due to anti-selection, i.e., possibly DR16Q-classified as a non-quasar. Candidates which consequently fell below pQSO=80% (~57K) were dropped. The Chandra Source Catalog v2 was added, but only as a supplement to the CSC v1.1 because v2 provides only stacked data for which the optical solution used by Milliquas cannot be calculated. 6.4b 19Dec19 Some extra processing of the new SDSS-DR16 data yielded 534 more type-I objects and fixed the astrometry of 381 objects which had been offset by up to 3 arcseconds. About 800 QSOs were flagged as host-dominated and so were reclassified to AGN. 6.4c 31Dec19 Quasars were added from publications to 31 December 2019. The 4XMM-DR9 XMM-Newton catalog was added and X-ray associations calculated, replacing 3XMM-DR8. The 2SXPS Swift XRT catalog was added and X-ray associations calculated, replacing 1SXPS. Gaia astrometry was removed from 18 quasars and 66 candidates which were in doublets (on the sky) for which Gaia had astrometry only for the other object. SDSS-DR16 redshifts more fully replaced earlier SDSS pipeline data. 6.5 14Jun20 Quasars were added from publications to 14 June 2020. Gaia-sourced parallaxes and proper motions were analyzed to see if they could identify false quasars. Legacy quasar publications were then group tested such that those with a high flag rate (>20% compared with 2% overall, signaling the presence of low-quality data) had their flagged objects dropped, provided, as a confirmation, that those objects also had no radio/X-ray associations. The counts of dropped objects were: -- 28 out of 40 (70%) from Zhan & Chen, 1987 & 1989 ChA&A -- 400 out of 916 (44%) from Iovino/Clowes/Shaver, 1996,A&AS,119,265 -- 50 out of 194 (26%) from Savage/Trew/Chen/Weston, 1984,MNRAS,207,393 -- 111 out of 517 (21%) from Drinkwater 1987. In total, 589 "quasars" were dropped for having parallaxes/proper motions. 136 SDSS-DR14 objects which were dropped by SDSS-DR16 were removed. About 1500 objects had their photometry supplemented from Pan-STARRS data. 6.6 30Aug20 Quasars were added from publications to 30 August 2020. The SDSS-DR16Q data (Lyke+ 2020) were incorporated. Combined with the DR16 pipeline data, these contributed ~200K new quasars beyond DR14 plus many valuable reclassifications of the SDSS-IV data. In processing this vast data pool, the author identified 37 new quasars not classified by DR16/DR16Q. These were added in Milliquas with ref_name="MQ" and ref_redshift="DR16QN"/"DR16". Data selection of DR16 pipeline data was by HMQ (Flesch 2015) rules, including choice of spectra. Data flagged with ZWARNING=256 (bad astrometry) were validated by testing and are included. Details of usage of the SDSS-DR16/DR16Q data will be included in a Milliquas paper in preparation (Flesch 2021). 7.0 30Sep20 Quasars were added from publications to 30 September 2020. SDSS-DR16 represented the conclusion of the eBOSS and BOSS quasar surveys, and that conclusion somewhat orphaned the leftover candidates from the SDSS-based photometric catalogs. Said candidates without any radio/X-ray/WISE associations were unlikely to be targeted in this decade, and so were dropped from Milliquas, 574,538 of them. Said candidates which did have WISE associations, numbering 35,086, were changed to display AllWISE names. These significant changes prompted this release to be numbered v7.0.Clean-ups were done on the uptake of SDSS-DR16Q/DR16 by Milliquas v6.6, notably 4,506 DR16Q quasars previous presented as candidates, were designated to be QSOs. Also, 404 low-quality pipeline objects which were presented as QSOs were dropped. WISEA photometric redshifts were recalculated using the DR16-augmented training set, and Pan-STARRS-based photometric redshifts were calculated for radio/X-ray associated candidates on the PS1 footprint (all-sky N of decl. S30) using the four-color method of 2015,PASA,32,10, Appendix 2. 222 candidates in a solid degree centered on J2033+412 in Cygnus were dropped. They are obvious stars, albeit near to background Galactic X-ray sources. 7.1 14Feb21 Quasars were added from publications to 14 February 2021. For quasar candidates, the pQSO (likelihood that the candidate is a quasar) threshold for inclusion into Milliquas was lowered to 60%. This was done to present more radio/X-ray associated candidates which were not available elsewhere. Audits on the inclusion of DR16Q into Milliquas led to tweaks of the selection of DR16Q objects. Other SDSS data were also audited. Also, all galaxy data are removed in order to focus exclusively on quasars. LAMOST-DR6 was added -- being pipeline-only data, its quasar classifications were accepted into Milliquas only when supported by radio/X-ray/WISEA pQSOs. 4XMM-DR10 X-ray sources were added, replacing DR9. 7.2 02May21 Quasars were added from publications to 30 April 2021. The VLASS Quick Look radio catalog was included, which added 34189 new radio core associations and 6793 probable double radio lobe associations. Ongoing audits of SDSS and LAMOST quasars resulted in a few additions and drops. Some WISEA-supported SDSS/LAMOST pipeline quasars were accepted which were otherwise marginal. Also, some likely galaxies were removed. 7.3 31Oct21 Quasars were added from publications to 31 October 2021. 17 classified quasars were dropped as moving stars (Gaia-DR2 flagged and confirmed on legacy DSS charts), 4 as galaxies, and 1 line poacher. 42,637 quasar candidates for which Gaia-DR2 shows proper motion or parallax, have been dropped for efficiency. 1365 quasars and ~100K candidates without Gaia-DR2 J2000 were reconciled to Pan-STARRS or SDSS J2000 with an average positional shift of ~0.1 arcsec. About 400 very faint (r>22) legacy quasars were positionally tweaked by comparing to DES and Pan-STARRS images, usually ~1 arcsec, some more. Selection and processing tweaks done on candidates, adding a net 93. AGES (Kochanek+ 2012) was reloaded using the CDWFS X-ray survey (Masini+ 2020,ApJS,251,2) to support object selection. AGES did not publish their spectra; 368 of their objects were switched to cite DR16Q which shows spectra. RACS (Hale+ 2021, arXiv:2109.00956) radio associations were added. RASS (ROSAT All-Sky Survey) X-ray data was dropped, as it has become clear over time that its resolution is too coarse to confidently identify sources. OzDES1 (Tie+ 2017,AJ,153,107) were fully replaced by OzDES2. 4XMM-DR11 X-ray sources were added, replacing 4XMM-DR10. 7.4 12Dec21 Quasars were added from publications to 12 December 2021. SDSS-DR17 was processed, with 1003 new quasars and 266 new MaNGA AGN added. The eFEDS AGN catalog was processed, with 532 new quasars added. Only the best-quality data were used (5029#); of which, 1139 were new objects. Redshift/photometry cut-offs were used on those to avoid galaxy contamination. WISEA-only candidates were removed to avoid repeating candidates from other catalogs, which resulted in 448,009 candidates removed. The only candidates presented are those with radio/X-ray associations calculated by this work. More Pan-STARRS astrometry was added. 1219 RACS associations with bad RACS names (wrong hemisphere) were fixed. 7.5 30Apr22 Quasars were added from publications to 30 April 2022. The LAMOST DR7 pipeline added 646 QSOs supported by radio/X-ray/WISEA association. A search revealed six earlier (2011-2021) papers missed due to not being on ArXiv, paywalled data, or otherwise overlooked. The were added (yielding 156 new objects) and indexed below as AT20G, ICRFz, GB6hiz, Hdots1, Hdots2, and 4FGL3. Candidates selection was tweaked for efficiency with a net total of ~800 fewer objects. The citations 2MAGN (Zaw+,2019) and 6dAGN (Chen+,2022) classify faint nuclear emission. Their type-I & Kewley-criterion type-II objects were accepted into the catalog. HETDEX AGN of 2+ spectral lines were added into Milliquas after deduplication. 7.6 15Sep22 Quasars were added from publications to 31 August 2022. All objects/candidates calculated as having 80-100% likelihood of radio/X-ray association (RXpct) were included, including classified galaxies. This increased the Milliquas row count by ~50%. The threshold was increased to 80% to increase reliability. RXpct and Qpct (pQSO) were split into separate columns clarify the distinction for users. Gaia-DR3 QSO candidates (indexed as "GAIA3" below) with redshifts were matched to radio/X-ray detections, and those with calculated associations of 80%+ likelihood were added as candidates. Their redshifts were rounded to 0.1z to show that they are only approximate; because of the lack of spectral redshift, they could not be fully classified as QSOs in Milliquas. The classification of "q" (quasar candidate) was added to denote candidates which are 99% likely to be true QSOs, as per the method of Flesch 2015,PASA,32,10 Section 8. 4XMM-DR12 X-ray sources were added, replacing DR11. MIGHTEE spectral AGN (indexed as "MIGHTE" below) were added, but with cuts to avoid galaxy contamination: 2/5 MIGHTEE "True" tests required, and z>0.7. 7.7 15Oct22 See list of changes above.
The designation of the source as taken from the literature. Nameless radio/X-ray associated objects here utilize the J2000 position in "HHMMSS.SS+DDMMSS.S" for the convenience of the user. If needing a name for it, just prefix this value with "MQ ", e.g., MQ J000001.89+443053.8.
The Right Ascension of the quasar candidate in the selected equinox. This was given in J2000.0 decimal degrees to a precision of 10-7 degrees in the original table. That suits objects with Gaia-DR2 astrometry and accommodates a minuscule round-up to avoid truncation in use, but it is too precise for other objects, although it prevents inadvertent truncation when converting to sexagesimal.
The Declination of the quasar candidate in the selected equinox. This was given in J2000.0 decimal degrees to a precision of 10-7 degrees in the original table. That suits objects with Gaia-DR2 astrometry and accommodates a minuscule round-up to avoid truncation in use, but it is too precise for other objects, although it prevents inadvertent truncation when converting to sexagesimal.
The Galactic Longitude of the quasar candidate. This parameter has been added by the HEASARC and is converted from the provided equatorial position.
The Galactic Latitude of the quasar candidate. This parameter has been added by the HEASARC and is converted from the provided equatorial position.
The classification of the object, where the following abbreviations are used:
Q = QSO, type-I broad-line core-dominated, 792035 of these. A = AGN, type-I Seyferts/host-dominated, 42097 of these. B = BL Lac type object, 2803 of these. L = lensed quasar extra image with radio/X-ray, only 17 of these. K = NLQSO, type-II narrow-line core-dominated, 5959 of these. N = NLAGN, type-II Seyferts/host-dominated, 39331 of these. Incomplete, and includes an unquantified residue of legacy NELGs/ELGs/LINERs, plus some unclear AGN. This is the catch-all category. G = galaxy classified, without spectrum if no redshift, 169242 total. S = star classified, usually pipeline-only, 630 of these. q = best quasar candidates, 99% likely to be true QSOs, as per the method of Flesch 2015,PASA,32,10 Section 8. 50807 of these. R = radio association displayed. X = X-ray association displayed. 2 = double radio lobes displayed (declared by data-driven algorithm).
The red optical magnitude of the object. The type and source of this magnitude is specified in the optical_flag parameter value. Optical data are mostly from the ASP optical catalog (2017,PASA,34,25) which presents data from the APM (http://www.ast.cam.ac.uk/~mike/apmcat/), USNO-A and USNO-B (http://tdc-www.harvard.edu/catalogs/ub1.html), and the SDSS (https://sdss.org/). APM/USNO-A magnitudes were recalibrated from the original values as documented in 2004,A&A,427,387. As a result, these recalibrated USNO-A magnitudes are often used in preference to USNO-B. APM galaxies brighter than 17th magnitude are usually represented as far too bright due to PSF modeling. Integer magnitudes (e.g., 22.00) are estimates if both bands are integers or one band is empty. If the optical_flag parameter value contains r/b/g/i/v/u/z, then the magnitudes are from the object's source catalog, e.g., SDSS, 2QZ, etc. Note that many SDSS magnitudes are extinction-"corrected" ~0.3 mag brighter than observed.
The blue optical magnitude of the object. The type and source of this magnitude is specified in the optical_flag parameter value. Optical data are mostly from the ASP optical catalog (2017,PASA,34,25) which presents data from the APM (http://www.ast.cam.ac.uk/~mike/apmcat/), USNO-A and USNO-B (https://web.archive.org/web/20180529212008/http://www.nofs.navy.mil/), and the SDSS (https://sdss.org/). APM/USNO-A magnitudes were recalibrated from the original values as documented in 2004,A&A,427,387). As a result, these calibrated USNO-A magnitudes are often used in preference to USNO-B. APM galaxies brighter than 17th magnitude are usually represented as far too bright due to PSF modeling. Integer magnitudes (e.g., 22.00) can be estimates if both bands are integer or one band empty. If the optical_flag parameter value contains r/b/g/i/v/u/z, then the magnitudes are from the object's source catalog, e.g., SDSS, 2QZ, etc. Note that many SDSS magnitudes are extinction-"corrected" ~0.3 mag brighter than photometry.
This field contains coded information on the optical source properties, as follows:
p = optical magnitudes are POSS-I O (violet 4050A) and E (red 6400A). These are preferred because O is well-offset from E, and those plates were always taken on the same night, thus the red-blue color is correct even for variable objects. The epochs for these are 1950s. j = optical magnitudes are SERC J (Bj 4850A) and R (red 6400A) from the POSS-II or UKST surveys. Red-blue color is less reliable because the red and blue plates were taken in different epochs, i.e., years apart. b = blue magnitude is Vega 4400A (Johnson), red is 6400A (Cousins). g = blue magnitude is SDSS-type green 4900A, red is r 6200A. n = blue magnitude is Pan-STARRS green 4900A, red is r 6200A. d = magnitudes are DES DR2 AB g & r. u = blue magnitude is SDSS ultraviolet 3850A. v = red magnitude is visual, i.e., white, 5500A midpoint. i = red magnitude is infrared 7500A. z = red magnitude is infrared z 8600A. r = red magnitude is r 6200A. (blank) = red alone is 6400A (Cousins); if both magnitudes are present, then estimates. G = Gaia-DR2 astrometry shown, precessed to J2000 by CDS. If 'G' is alone then the magnitudes are Gaia RP & BP, or Gaia G if red band only. N = Pan-STARRS astrometry shown. If 'N' is alone, PS photometry also. + = variability nominally detected in both red/blue over multi-epoch data. m = proper motion detected. If from Gaia-DR2/3 ('G' also present in this field), then this is proper motion or parallax which usually signifies a star, but optical centroids can deflect within the optical gradient of a near moving neighbor or if either object is variable; some will be quasars. If not Gaia, it is from USNO-B which is nominal only. e = USNO-B1.0 "epoch 2000" projected location based on nominal proper motion, can miss true location by many arcsec. % = swap of two "unplugged" SDSS spectra which crossed wires (7 of these). ? = legacy "quasar" which however is probably not a quasar (4 of these). a = object is host-dominated with faint nuclear activity, such as an SDSS pipeline galaxy with an AGN subclass or AGN-classed elsewhere, see its citation. Milliquas class is 'A' if BROADLINE, else 'N'. (See broad_type.)
A coded representation for the point spread function (PSF) of the optical source in the red. The APM, USNO-B, and SDSS provide PSF class, albeit using different criteria. The codes are as follows:
- = point source / stellar PSF (APM notation: -1, here truncated) 1 = fuzzy / galaxy shape (APM notation: 1 and some 2) n = no PSF available, whether borderline or too faint to tell, etc. x = not seen or unclear in this band (although may show a Pan-STARRS magnitude)
A coded representation for the point spread function (PSF) of the optical source in the blue. The APM, USNO-B, and SDSS provide PSF class, albeit using different criteria. The codes are as follows:
- = point source / stellar PSF (APM notation: -1, here truncated) 1 = fuzzy / galaxy shape (APM notation: 1 and some 2) n = no PSF available, whether borderline or too faint to tell, etc. x = unseen / unclear in this band (fainter than plate depth, confused, etc.)
The redshift of the object, taken from the literature as specified in the ref_redshift parameter. Spectroscopic/grism redshifts are required for objects classified as Q/A/K/N/L and is optional for B (BL Lac type). Photometric redshifts are rounded to 0.100z (and can be identified by that rounding) and are either taken from the cited catalog or calculated here using the four-color method of Flesch 2015,PASA,32,10, Appendix 2, using 4 colors from SDSS ugriz, Pan-STARRS grizy (or orgriz with calibrated POSS-I O), or WISEA colors B-R, R-W1, W1-W2, and W2-W3. Photometric redshifts apply onto a quasar template mostly and not so well to galaxies. GAIA3 type=Q/A show the "QSOC" estimated redshift provided by Gaia-DR3, rounded here to 0.1z.
A character code for the literature reference from which the name was taken is indicated below. The meaning of any 4-digit numerical code can be found in the "HMQ-references.txt" file of the author's Half Million Quasars Catalog (HMQ: Flesch 2015,PASA,32,10) at http://cdsarc.u-strasbg.fr/ftp/pub/cats/VII/273/refs.dat. The 4-digit reference codes for galaxies and stars are indexed in the file "MORX-references.txt" from Flesch 2016,PASA,33,52.
Code (No. of names, No. of redshifts): Reference 2dF (2717,5536): 2dF galaxy survey, Colless M. et al., 2001,MNRAS,328,1039 2MAGN (7,4552): 2MASS AGN, Zaw/Chen/Farrar, 2019,ApJ,872,134 2MRS (1112,3583): Huchra J.P. et al., 2012,ApJS,199,26, http://tdc-www.harvard.edu/2mrs/ 2QZ (27578,24213): Croom S.M. et al., 2004,MNRAS,349,1397 2SLAQ (10675,8992): Croom S.M. et al., 2009,MNRAS,392,19 3FGL (16,11): Fermi cleanups, Paiano S. et al., 2017,ApJ,851,135 3FGL2 (21,19): Fermi cleanups II, Paiano S. et al., 2019,ApJ,871,162 3HSP (820,986): 3HSP blazars, Chang Y.-L. et al., 2019,A&A,632A,77 3XLSS (25,25): The XXL Survey, Pierre M. et al., 2016,A&A,592A,1P 4FGL1 (15,3): Fermi cleanups, de Menezes R. et al., 2019,A&A,630A,55 4FGL2 (19,23): Fermi cleanups X, de Menezes R. et al., 2020,Ap&SS,365,12 4FGL3 (19,44): Gamma-ray blazars, Peña-Herazo H.A. et al., 2021,AJ,162,177 4FGL4 (22,20): Fermi spectra, Olmo-García A. et al., 2022,arXiv:2209.06518 4LAC (435,382): Fermi AGN v4 DR3, Fermi-LAT collab., 2022,arXiv:2209.12070 6dF (5999,15839): 6dF galaxy survey, Jones D.H. et al., 2009,MNRAS 399,683 6dAGN (0,4433): 6dF AGN, Chen/Zaw/Farrar/Elgamal, 2022,ApJS,258,29 AAOz (1491,1498): AAOmega XXL-South, Lidman C. et al., 2016,PASA,33,1 ABQ (115,119): AllBRICQS bright, Onken C.A. et al., 2022,arXiv:2209.09342v1 AGEL (60,60): Strongly lensed QSOs, Tran K.H. et al., 2022,AJ,164,148 AGES (1758,1758): AGES survey, Kochanek C.S. et al., 2012,ApJS,200,8 AGNELL (2,3): DES lenses, Agnello A. et al., 2015,MNRAS,454,1260 AGNELA (1,1): SDSS J1433+6007 4-lens, Agnello A. et al., 2018,MNRAS,474,3391 AGNEL2 (13,13): VST-Gaia QSO pairs, Agnello A. et al., 2018,MNRAS,475,2086 AKARI (1,1): overlooked luminous quasar, Aoki K. et al., 2011,PASJ,63,457 ALMA (4,4): ALMA hi-z, Roberto Decarli R. et al., 2018,ApJ,854,97 ANDIKA (2,2): Hi-z starbursts, Andika I.T. et al., 2020,ApJ,903,34 ANGUIT (1,1): COSMOS lens, Anguita T. et al., 2009,A&A,507,35 ASDA2 (3,10): Dual AGN II, Zhang Y.-W. et al., 2021,AJ,162,289 ASDA3 (0,13): Dual AGN III, Zhang Y.-W. et al., 2021,AJ,162,276 AT20G (59,65): radio quasars, Mahony E.K. et al., 2011,MNRAS,417,2651 ATel (5,6): Astronomers Telegraph posts, http://www.astronomerstelegram.org ATHENS (86,108): VIPERS AGN SEDs, Pouliasis E. et al., 2020,MNRAS,495,1853 ATLAS (281,326): Mao M.Y. et al., 2012,MNRAS,426,3334 BAHM (24,24): dust-reddened QSOs, Banerji M. et al., 2015,MNRAS,447,3368 BASS2 (53,164): Swift-BAT AGN DR2 catalog, Koss M. et al., 2022,ApJS,261,2 BERGHE (1,1): Pan-STARRS lens, Berghea C.T. et al., 2017,ApJ,844,90 BGGFC (4,4): COSMOS hi-z, Boutsia K. et al., 2018,ApJ,869,20 BLAZZ (0,8): Blazar redshifts, Goldoni P. et al., 2021,A&A,650,A106 BMCGCS (1,1): Belladitta S. et al., 2019,A&A,629A,68 BMCS (1,1): Blazar at z>6, Belladitta S. et al., 2020,A&A,635L,7 BQLS (11,11): BOSS QSO lenses & pairs, More A. et al., 2016,MNRAS,456,1595 BZCAT (4,2): BZCAT, Massaro+, 2015, http://cdsarc.u-strasbg.fr/ftp/cats/VII/274 C-COSM (180,180): Chandra COSMOS IDs, Marchesi S. et al., 2016,ApJ,817,34 COOLL (1,1): 25.9" lensed QSO, Martinez M. et al., 2022,arXiv:2209.03972v1 ChaMP (284,277): Trichas M. et al., 2012,ApJS,200,17 DABAST (1,1): Diaz-Santos T. et al., 2018,Sci,362,1034 Dart (26,25): Heavily Obscured QSOs, Hviding R. et al., 2018,MNRAS,474,1955 DDC2 (14,14): variable AGN, De Cicco D. et al., 2019,A&A,627A,33 DES (1,1): Dark Energy hi-z, Reed S.L. et al., 2015,MNRAS,454,3952 DESQQ (26,26): STRIDES lenses, Anguita T. et al., 2018,MNRAS,480,5017 DESQQ2 (12,12): STRIDES lenses, Treu T. et al., 2018,MNRAS,481,1041 DESQQ3 (2,2): QSO Pair at z=5.66, Yue/Fan/Yang/Wang, 2021,ApJ,921,27 DESQQ4 (4,4): double/quad DESI QSOs, Dawes C. et al., 2022,arXiv:2208.06356 DPeake (711,1568): Double-peaked NELGs, Ge J.-Q. et al., 2012,ApJS,201,31 DR12 (15,17): SDSS-DR12 pipeline, Alam S. et al., 2015,ApJS,219,12 DR12Q (472,246): SDSS-DR12Q visual, Paris I. et al., 2017,A&A,597,79 DR14 (47,79): SDSS-DR14 pipeline, Abolfathi B. et al., 2018,ApJS,235,42 DR14Q (1527,1534): SDSS-DR14Q visual, Paris I. et al., 2018,A&A,613A,51 data at https://data.sdss.org/sas/dr14/eboss/qso/DR14Q DR16 (132414,485728): SDSS-DR16 pipeline, Ahumada R. et al., 2020,ApJS,249,3 data at https://data.sdss.org/sas/dr16/sdss/spectro/redux DR16Q (719239,397442): SDSS-DR16Q visual, Lyke B. et al., 2020,ApJS,250,8 2 files, data at https://data.sdss.org/sas/dr16/eboss/qso/DR16Q DR16QN (0,2148): same as DR16Q, using the QuasarNET redshift supplied. DR17 (1054,1321): SDSS-DR17, Abdurro'uf et al., 2022,ApJS,259,35, pipeline, includes MaNGA AGN, data in https://data.sdss.org/sas/dr17 DR7 (16,143): SDSS-DR7 pipeline, Abazajian K.N. et al., 2009,ApJS,182,543 DR7Q (1968,200): SDSS-DR7Q visual, Schneider D. et al., 2010,AJ,139,2360, data on SDSS, with Table 5 available at journal (AJ) page. DUALQ (1,1): Dual QSOs HSC, Silverman J.D. et al., 2020,ApJ,899,154 DUHIZ (2,2): DECaLS-UKIRT hi-z, Wang F. et al., 2017,ApJ,839,27 Dusty (11,11): Dusty Starbursts, Rodighiero G. et al., 2019,ApJ,877L,38R DUz6 (18,18): DESI & UKIRT hi-z, Wang F. et al., 2019,ApJ,884,30 eFEDS (532,532): eFEDS AGN, Liu T. et al., 2022,A&A,661A,5 eHAQ (82,80): Extended High AV, Krogager J.-K., 2016,ApJ,832,49 ELQ-PS (216,215): ELQS on PS1, Schindler J.-T. et al., 2019,ApJS,243,5 ELQS-N (38,38): ELQS in NGC, Schindler J.-T. et al., 2018,ApJ,863,144 ELQS-S (125,125): ELQS in SGC, Schindler J.-T. et al., 2019,ApJ,871,258 ENEAR (26,42): Wegner G. et al., 2003,AJ,126,2268 FISCBA (1,1): HST lens, Fischer/Schade/Barrientos, 1998,ApJ,503,L127 FLES40 (40,0): Salvaged QSOs, Flesch E.W., 2021,MNRAS,504,621 FYNBO (1,1): LiBAL QSO, Fynbo J.P.U. et al., 2020,A&A,634A,111 GAIA1 (21,0): Gaia DR1, Gaia Collaboration et al., 2016,A&A,595A,1 GAIA2 (235,231): Gaia DR2, Gaia Collaboration et al., 2018,A&A,616,A1, (GAIA data as presented by SIMBAD, http://simbad.u-strasbg.fr/simbad) GAIA3 (20975,23621): Gaia DR3 QSO candidates, Gaia Collaboration et al., 2022,arXiv:2206.05681, https://gea.esac.esa.int/archive GAMA (64,64): Low-mass AGN, Salehirad/Reines/Molina, 2022,ApJ,937,7 GB6hiz (7,6): z>4 blazars, Caccianiga A. et al., 2019,MNRAS,484,204 GEIER (1,1): Geier S.J. et al., 2019,A&A,625L,9 GGLS (4,5): Gaia GraL, Krone-Martins A. et al., 2019,arXiv:1912.08977 GL2hiz (2,2): Two lensed hi-z, Desira C. et al., 2022,MNRAS,509,738 GLDD (1,1): Lensed QSO data-driven, Ostrovski F. et al., 2017,MNRAS,465,4325 GLIKMA (30,30): red WISE QSOs, Glikman E. et al., 2018,ApJ,861,37 GLOH (1,1): Grav Lensed Objs HSC, Jaelani A.T. et al., 2021,MNRAS,502,1487 GLRED (1,1): lensed red QSO, Glikman E. et al., 2018,arXiv:1807.05434 GMM1 (1,1): Gaussian Mixture QSO,Wagenveld J.D. et al.,2022,A&A,660A,22 GPQ (199,198): Galactic plane, Fu Y. et al., 2022,ApJS,261,32 GQ (2,2): serendipitous binary, Altamura E. et al., 2020,AJ,159,122 GRAL4 (10,10): Gaia GraL quads, Stern D. et al., 2021,AJ,921,42 GUTI (1,1): not a ULX, Gutiérrez C.M., 2013,A&A,549,A81 GZPM (23,23): Gaia zero pm, Heintz K.E. et al., 2020,A&A,644A,17 H-DOGs (16,16): Herschel DOGs, Riguccini L.A. et al., 2019,AJ,157,233 HAQ (2,2): High AV serendipitous, Heintz K.E. et al., 2016,AJ,152,13 HAQC (1,1): High AV in COSMOS, Heintz K.E. et al., 2016,A&A,595,13 Hdots1 (8,5): H-alpha dots, Kellar J.A. et al., 2012,AJ,143,145 Hdots2 (17,18): H-alpha dots II, Salzer J.J. et al., 2020,AJ,160,242 HE2QS (103,103): HeII quasar survey, Schmidt T.M. et al., 2017,ApJ,847,81 HE2QS2 (5,5): HeII HST/COS quasars, Worseck G. et al., 2019,ApJ,875,111 HEINTZ (1,1): dusty absorbed QSO, Heintz K.E. et al., 2018,A&A,615A,43 HETDEX (1144,1169): HETDEX AGN, Liu C. et al., 2022,ApJS,261,24 HIZ7.5 (1,1): QSO z=7.5, Bañados E. et al., 2018,Natur,553,473 HSC (3,3): Low-luminosity QSOs, Niida M. et al., 2020,ApJ,904,89 HSDQ (4,4): z~5 quasars, Shin/Im/Kim/Jiang, 2022,arXiv:2208.00612 HSTvar (42,42): variable AGN, Pouliasis E. et al., 2019,MNRAS,487,4285 ICECUB (9,11): IceCube spectra, Paiano S. et al., 2021,MNRAS,504,3338 ICRFz (90,112): ICRF quasars, Titov O. et al., 2017,AJ,153,157 IGMCP (10,10): IGM close pairs, Rorai A. et al., 2017,Sci,356,418 IKEDA (1,1): Ikeda H. et al., 2017,ApJ,846,57 ILT1 (20,20): LoTSS quasars, Gloudemans A.J. et al., 2022,arXiv:2210.01811 IMDS (3,3): IR medium-deep hi-z VII, Shin S. et al., 2020,ApJ,893,45 IMS (1,1): IR medium-deep hi-z, Kim Y. et al., 2015,ApJ,813,35 IMS2 (10,11): IR medium-deep hi-z, Kim Y. et al., 2019,ApJ,870,86 IMS3 (2,2): IR medium-deep hi-z, Kim Y. et al., 2022,arXiv:2207.12282 INAF (1,1): UV bright hi-z, Grazian A. et al., 2020,ApJ,897,94 J1030 (49,49): AGN in J1030 field, Marchesi S. et al., 2021,A&A,656,A117 JERAM (1,1): extremely bright, Jeram S. et al., 2020,ApJ,899,76 JPLUS (24,24): luminous Ly, Spinoso D. et al., 2020,A&A,643A,149 K4K (2,2): K4000 bz, Uwitonze/Nkundabakura/Mutabazi, 2021,IAUS,356,355 KHOR1 (7,6): 3XMM hi-z, Khorunzhev G.A. et al., 2017,AstL,43,135 KHOR2 (11,11): 3XMM hi-z, Khorunzhev G.A. et al., 2019,AstL,45,411 KHOR3 (1,1): X-ray luminous, Khorunzhev G.A. et al., 2021,AstL,47,123 KODQ3 (4,4): KODIAQ DR3, O'Meara J.M. et al., 2021,AJ,161,45 KOVACS (1,1): bright QSO behind Milky Way, Kovács T. et al., 2019,RNAAS,3,3 LAMDR5 (0,1075): LAMOST-DR5, pipeline, http://dr5.lamost.org LAMDR6 (2851,2852): LAMOST-DR6, pipeline, http://dr6.lamost.org LAMDR7 (203,203): LAMOST-DR7, pipeline, http://dr7.lamost.org LAMQ1 (680,621): LAMOST QUASAR DR1, Ai Y.L. et al., 2016,AJ,151,24 LAMQ3 (6679,6568): LAMOST QUASAR DR3/DR2, Dong X.Y. et al., 2018,AJ,155,189 LAMQ5 (7931,7929): LAMOST QUASAR DR5/DR4, Yao S. et al., 2019,ApJS,240,6 LEMON (33,33): 24 Gaia lenses, Lemon C. et al., 2018,MNRAS,479,5060 LEMON2 (25,25): 22 Gaia lenses, Lemon/Auger/McMahon, 2019,MNRAS,483,4242 LEMON3 (52,51): STRIDES lenses etc, Lemon C. et al., 2020,MNRAS,494,3491 LEMON4 (155,155): Gaia lenses etc, Lemon C. et al., 2022,arXiv:2206.07714v1 LGGS (13,13): M31/M33 area, Massey/Neugent/Levesque, 2019,AJ,157,227 LIDMAN (1,1): SN Host Galaxy redshifts, Lidman C. et al., 2013,PASA,30,1 LIN (1,1): DES lens, Lin H. et al., 2017,ApJ,838,15 LIRAS (169,154): LoCuSS IR AGNs, Xu, L. et al., 2015,ApJS,219,18 LOZAGN (38,10992): Low-redshift AGN, Liu H.-Y. et al., 2019,ApJS,243,21 LSSA (2,1): 2 lenses, Lucey/Schechter/Smith/Anguita, 2018,MNRAS,476,927 LUMIz5 (66,66): Luminous hi-z, Yang J. et al., 2019,ApJ,871,199 LUMQ (1,1): Most luminous quasar, Onken C. et al., 2022,arXiv:2206.04204 M31UV (1,1): UV flare QSO on M31, Meusinger H. et al., 2010,A&A,512,A1 MAGN1 (1,7): MaNGA type-1 AGN, Cortes-Suárez et al., 2022,MNRAS,514,3626 MALS-N (72,71): MALS-NOT QSOs, Krogager J.-K. et al., 2018,ApJS,235,10 MALS-S (150,152): MALS-SALT QSOs, Gupta N. et al., 2022,ApJ,929,108 MFJC (52,51): McGreer I.D., Fan X., Jiang L. & Cai Z., 2018,AJ,155,131 MIGHTE (81,81): MIGHTEE faint AGN, Whittam I.H. et al., 2022,MNRAS,516,245 MQ (486255,261181): MILLIQUAS, original data in this catalog,Flesch E.,2022 NBCKDE (2549,2326): Richards G.T. et al., 2009,ApJS,180,67 NBCKv3 (15866,14069): NBCKDE v3, Richards G.T. et al., 2015,ApJS,219,39 NED (21,15): NASA/IPAC Extragalactic Database, https://ned.ipac.caltech.edu NLTT (1,0): Luyton moving stars, Salim S. & Gould A., 2003,ApJ,582,1011 OBHIZ (1,1): obscured high-z, Endsley D. et al., 2022,arXiv:2206.00018v1 OGLE2 (2,2): OGLE quasars, Kozlowski S. et al., 2019,ApJ,878,115 OVRLAP (5,5): SDSS overlap hi-z QSOs, Jiang L. et al., 2015,AJ,149,188 OzDES2 (1233,1259): OzDES-DR2 QSOs, Lidman C. et al., 2020,MNRAS,496,19 P352-1 (1,1): P352-15, Bañados E. et al., 2018,ApJ,861L,14 PETERS (226,224): photo special, Peters C.M. et al., 2015,ApJ,811,95 PFTS (2,11): blazar spectroscopy, Paiano S. et al., 2020,MNRAS,497,94 PGC (85675,1323): Principal Galaxy Catalog,Paturel G. et al.,2003,A&A,412,45 PHILLI (1,0): MERLIN lens, Phillips P.M. et al., 2000,MNRAS,319,L7 PRFhiz (39,39): PR Forests hi-z, Guarneri F. et al., 2021,MNRAS,506,2471 PS1 (63,63): PAN-STARRS1 hi-z, Bañados E. et al., 2016,ApJS,227,11 PS1hiz (1,1): Tang, Ji-Jia et al., 2017,MNRAS,466,4568 PS1MAZ (6,6): Mazzucchelli C. et al., 2017,ApJ,849,91M PSO (3,3): PAN-STARRS z-dropouts, Venemans B.P. et al., 2015,ApJ,801L,11V QLSV (22,20): QUEST-La Silla, Sánchez-Sáez P. et al., 2019,ApJS,242,10 QPQ10 (70,70): Quasar pair DB, Findlay J.R. et al., 2018,ApJS,236,44 QUBNIR (16,17): QUBRICS NIR spectra, Cupani G. et al., 2022,MNRAS,510,2509 QUBRF (187,187): QUBRICS PRF, Guarneri F. et al., 2022,arXiv:2209.07257 QUBRIC (91,91): QUBRICS I, Calderone G. et al., 2019,ApJ,887,268 QUBRIX (249,252): QUBRICS II, Boutsia K. et al., 2020,ApJS,250,26 RBS (3,3): Laporte N. et al., 2017,ApJ,851,40 Redden (25,25): Reddened QSOs, Temple M.J. et al., 2019,MNRAS,487,2594 REQ4 (6,6): Reionization-Era quasars, Yang J. et al., 2019,AJ,157,236 REQ7 (1,1): Reionization-Era QSO z=7.5,Yang J. et al., 2020,ApJ,897,14 RFhiz (17,17): Random Forests, Wenzl L. et al., 2021,AJ,162,72 RLQ (4,3): Tuccillo D./Gonzalez-Serrano J.I./Benn C.R., 2015,MNRAS,449,2818 RSG (1,1): Dorn-Wallenstein T.Z. & Levesque E., 2017,IAUS,329,376 S82X (71,75): Stripe 82 AGN, LaMassa S.M. et al., 2019,ApJ,876,50 S82XRQ (8,8): Red Quasars, LaMassa S.M. et al., 2017,ApJ,847,100 SAGE1 (1,1): SAGE IR AGN, Hony S. et al., 2011,A&A,531A,137 SCULPT (2,3): Sculptor X-ray, Arnason R. M. et al., 2019,MNRAS,485,2259 SDLENS (3,3): SDSS Lenses, Williams P.R. et al., 2018,MNRAS,477L,70 SDSSHI (6,6): SDSS hi-z, Jiang L. et al., 2016,ApJ,833,222 SELMAN (1,1): serendipitous, Selman F.J. et al., 2020,AN,341,26 SFM201 (1,1): Schulze S. et al., 2012,A&A,546,20 SHELLQ (33,33): Subaru hi-z, Matsuoka Y. et al., 2018,PASJ,70S,35 SHELQ3 (28,28): Subaru hi-z, Matsuoka Y. et al., 2019,ApJ,883,183 SHELQ4 (69,69): Subaru hi-z, Matsuoka Y. et al., 2022,ApJS,259,18 SHELQS (30,30): SHELLQS hi-z, Matsuoka Y. et al., 2018,ApJS,237,5 SHELz7 (1,1): SHELLQS z=7, Matsuoka Y. et al., 2019,ApJ,872L,2 SMhiz (140,140): Luminous SkyMapper, Onken C.A.+, 2022,MNRAS,511,572 SOLARZ (13,13): AllWISE anomalies, Solarz A. et al., 2020,A&A,642A,103 SPIN18 (1,1): KiDS-SQuaD lens, Spiniello C. et al., 2018,MNRAS,480,1163 SPIN19 (2,2): 2 lensed quasars, Spiniello C. et al., 2019,MNRAS,485,5086 SQLS (36,30): SDSS DR7 QSO Lens Search, Inada N. et al., 2012,AJ,143,119 SQUAD (13,13): UVES DB DR1, Murphy M.T. et al., 2019,MNRAS,482,3458 SRG1 (2,2): SRG Orbital Observatory 1st, Khorunzhev G.A. et al., 2020,AstL,46,149 SRG2 (4,4): SRG/eROSITA, Dodin A.V. et al., 2020,AstL,46,429 SRG3 (7,7): SRG RTT-150, Bikmaev I.F. et al., 2020,AstL,46,645 SRG4 (4,8): SRG ART-XC AGN, Zaznobin I.A. et al., 2021,AstL,47,71 SRGA (3,8): SRG ART-XC/eROSITA AGN, Uskov G.S. et al., 2022,arXiv:2208.10963 SSLENS (3,3): South sky lenses, Spiniello C. et al., 2019,MNRAS,483,3888 SUV (22,22): SDSS-ULAS/VHS QSOs, Yang J. et al., 2017,AJ,153,184 SXDF (42,42): Subaru-XMMDF redshifts, Simpson C. et al., 2012,MNRAS,421,3060 SXDS (307,306): Subaru-XMMDF spectra, Akiyama M. et al., 2015,PASJ,67,82 UGC (48,704): UGC Galaxies, Cotton W.D. and Condon J.J., 1999,ApJS,125,409 ULTRA (1,1): Ultraluminous hi-z, Wu, X.-B. et al., 2015,Nature,518,512 UNIONS (14,14): UV-NIR QSO lens, Chan J.H.H. et al., 2022,A&A,659,140 UVQS (442,511): UV QSOs, Monroe T.R. et al., 2016,AJ,152,25 VAHIZ (2,2): VST ATLAS hi-z, Carnall A.C. et al., 2015,MNRAS,451,L16 VAHIZ2 (1,1): bright z>6 QSOs, Chehade B. et al., 2018,MNRAS,478,1649 VAHIZ3 (1,1): VST-ATLAS lens, Schechter P.L. et al., 2018,RNAAS,2b,21 VAQL (11,11): VST-ATLAS quasar systems,Schechter P.L. et al.,2017,AJ,153,219 VARAGN (5,4): GALEX var, Wasleske/Baldassare/Carroll, 2022,arXiv:2205.00547 VDES (8,8): VISTA Dark Energy QSOs, Reed S.L. et al., 2017,MNRAS,468,4702 VDES2 (2,2): more VHS-DES quasars, Reed S.L. et al., 2019,MNRAS,487,1874 VIKING (4,4): VIKING IR, Venemans, G.A. et al., 2015,MNRAS,453,2259 VIPERS (241,284): VIPERS PDR-2, Scodeggio M. et al., 2018,A&A,609A,84 VMC (34,34): Magellanic IR QSOs, Ivanov V.D. et al., 2016,A&A,588,A93 VMC2 (10,10): Magellanic dusty, Pennock C.M. et al., 2022,MNRAS,515,6046 W2M2 (27,25): WISE-2MASS red QSOs, Glikman E. et al., 2022,ApJ,934,119 WARSAW (3,3): OGLE lens, Kostrzewa-Rutkowska Z. et al.,2018,MNRAS,476,663 WERTZ (1,1): Gaia GraL lens, Wertz O. et al., 2019,A&A,628A,17 WGD (2,2): DES/Gaia lenses, Agnello A. et al., 2018,MNRAS,479,4345 WILLIG (1,1): Williger, G., 2020, p comm., data on LJMU Robotic Telescope WISEA (32018,0): AllWISE QSO candidates, Secrest N. et al.,2015,ApJS,221,12 WISEHI (72,70): Hi-z QSOs from WISE, Wang F. et al., 2016,ApJ,819,24 WOLF1 (1,0): most ultraluminous QSO, Wolf C. et al., 2018,PASA,35,24 WOLF2 (18,18): hi-z ultraluminous QSOs, Wolf C. et al., 2020,MNRAS,491,1970 WYFH (1,1): z=7.642 quasar, Wang F. et al., 2021,ApJ,907,1 XDQSO (19325,0): SDSS-XDQSO, Bovy J. et al., 2011,ApJ,729,141 XLSS (324,132): Stalin C.S. et al., 2010,MNRAS,401,294 XMM2 (10,10): 2XMM-Newton cross-search, Combi J.A. et al., 2011,Ap&SS,331,53 XMMSMC (6,6): SMC quasars, Maitral C. et al., 2019,A&A,622A,29 XMSS (188,154): Barcons X. et al., 2007,A&A,476,1191 XWAS (513,476): Esquej P. et al., 2013,A&A,557,A123 XXL (57,57): bright X-ray stellar, Fotopoulou S. et al., 2016,A&A,592A,5 YQLF (25,25): deep CFHT QSOs, Yang J. et al., 2018,AJ,155,110 YSZ (0,414): Type 2 QSOs IDd, Yuan/Strauss/Zakamska, 2016,MNRAS,462,1603 z6.51 (1,1): lensed quasar z=6.51, Fan X. et al., 2019,ApJ,870L,11 z6.82 (1,1): radio-loud z=6.82, Bañados E. et al., 2021,ApJ,909,80 z7.02 (1,1): lensed quasar z=7.02, Wang F. et al., 2018,ApJ,869L,9The citation for the classification (e.g., that the object is a quasar) can be from either the name or redshift citation. Four-digit numeric citations can be found in the HMQ (2015,PASA,32,10) references list.
A character code for the literature reference from which the redshift was taken, using the same rubric as used for the ref_name parameter (q.v.).
This field contains the calculated percent likelihood that the shown radio/X-ray detection(s) is (are) truly associated with the object. These values are calculated as described in Flesch & Hardcastle, 2004,A&A,427,387.
This field contains the pQSO, the calculated likelihood that this optical object is a QSO, in percent, based on radio/X-ray association and optical photometry, plus WISEA analysis where applicable. This is not relevant for published quasars, but it shows the outcome of the algorithm's calculation. Any original authors' estimation is not included in this pQSO.
The identification of the best core radio detection associated with the quasar candidate, if any.
This is the identification of the best X-ray detection (i.e., the highest probability X-ray source associated with the quasar candidate, if any), but it can also be the identification of a radio lobe, if the radio_name parameter for the object itself contains the name of a radio lobe.
Radio/X-ray detections come from the following catalogs (and their respective home pages):
FIRST: VLA FIRST survey, 13Jun05 version, https://sundog.stsci.edu VLA (abbrev. of VLASS1QLCIR): VLASS Quick Look, https://cirada.ca/catalogues RACS: Rapid ASKAP Continuum Survey, 2021,PASA,38,58, main source file. RACD: RACS as above, but from the main detection ("Gaussian") file. NVSS: NRAO VLA sky survey, https://www.cv.nrao.edu/nvss SUMSS: Sydney U. Molonglo, http://www.astrop.physics.usyd.edu.au/sumsscat/ MGPS: Molonglo galactic plane, http://www.astrop.physics.usyd.edu.au/mgpscat/ ROSAT catalogs available from http://cdsarc.u-strasbg.fr/cats/IX.htx are: - IX/28A is 1RXH: ROSAT HRI (high resolution imager) - IX/30 is 2RXP: ROSAT PSPC (position sensitive proportional counter) 2RXF: https://heasarc.gsfc.nasa.gov/W3Browse/rosat/rospspcftot.html 1WGA: White, Giommi & Angelini, https://heasarc.gsfc.nasa.gov/wgacat/ CXOG: Chandra ACIS source catalog, Wang S. et al., 2016,ApJS,224,40 CXO: Chandra Source Catalog v1.1, https://cxc.harvard.edu/csc 2CXO: Chandra Source Catalog v2, https://cxc.harvard.edu/csc CXOX: XAssist Chandra source list, https://asd.gsfc.nasa.gov/xassist/ 2XMM/2XMMi: XMM-Newton DR3, http://cdsarc.u-strasbg.fr/cats/IX.htx IX/39&40 4XMM: XMM-Newton DR12, https://www.cosmos.esa.int/web/xmm-newton/xsa XMMSL: XMM-Newton Slew Survey Release 2.0, same attribution as 4XMM XMMX: XAssist XMM-Newton source list, https://asd.gsfc.nasa.gov/xassist/ 2SXPS: Swift X-ray Point Source catalog, https://www.swift.ac.uk/2SXPSOptical field solutions are calculated from the raw source positions of all these catalogs (except 2CXO) as described in the author's MORX paper (2016,PASA,33,52).
The identification of the radio lobe (as indicated by a "2" in the broad_type parameter) or an additional radio or X-ray identification associated with the quasar candidate, if any.
An additional identification of the radio lobe (as indicated by a "2" in the broad_type parameter) or an extra X-ray identification associated with the quasar candidate, if any.
The HEASARC Browse object classification, based on the information given in the broad_type parameter.