J/MNRAS/396/223ivo://CDS.VizieR/J/MNRAS/396/223doi:10.26093/cds/vizier.73960223CDSD'Abrusco R.Longo G.Walton N.A.2024-07-09T20:15:15Z2011-03-01T16:20:23ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frquasarssurveysvisible-astronomysloan-photometryWe present a method for the photometric selection of candidate quasars in multiband surveys. The method makes use of a priori knowledge derived from a subsample of spectroscopic confirmed quasi-stellar objects (QSOs) to map the parameter space. The disentanglement of QSOs candidates and stars is performed in the colour space through the combined use of two algorithms, the probabilistic principal surfaces and the negative entropy clustering, which are for the first time used in an astronomical context. Both methods have been implemented in the voneural package on the Astrogrid Virtual Observatory platform. Even though they belong to the class of the unsupervised clustering tools, the performances of the method are optimized by using the available sample of confirmed quasars and it is therefore possible to learn from any improvement in the available 'base of knowledge'. The method has been applied and tested on both optical and optical plus near-infrared data extracted from the visible Sloan Digital Sky Survey (SDSS) and infrared United Kingdom Infrared Deep Sky Survey-Large Area Survey public data bases. In all cases, the experiments lead to high values of both efficiency and completeness, comparable if not better than the methods already known in the literature. A catalogue of optical candidate QSOs extracted from the SDSS Data Release 7 Legacy photometric data set has been produced.2009MNRAS.396..223Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/396/223CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)http://www.sdss.org : SDSS Home Pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/396/223https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/396/223http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/396/223https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/396/223https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/396/223http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/396/223GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/396/223/qsos (QSO candidates in the SDSS stripes examined)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/396/223/qsos?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/396/223/qsos?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/396/223/qsos?GETtext/xml+votable180.050000true236.23726-0.557170.0055555555555555561/5 8 10 27 2/16-17 19 25 28 36 38 103 107 3/72-73 75 97 116 150 176-178 184 407 409-411 421 423 427 491 494 506 4/296-297 299 399 468-469 472 592 594-595 607 624 626 629 631-632 634 637 716 718 720 722 724 728 740 744-746 1109-1110 1113 1129-1130 1174 1193-1194 1365-1367 1375 1397 1399 1449 1599 1621-1623 1625-1627 1635 1690-1691 1701-1703 1705-1707 1877 1958 1961-1963 1980 1982-1983 2031 2042 5/0 136-138 1192-1193 1195 1540-1542 1548-1549 1551 1585 1588-1589 1593 1684-1685 1728-1729 1732-1733 1880-1882 1884 1896-1898 1900-1901 2372 2374-2375 2389 2391 2397 2399 2421-2423 2500-2502 2508 2510 2515 2521 2523 2532 2534 2540 2542 2545 2547 2553 2555-2556 2558 2868-2870 2876 2878 2900 2902 2908 2910 2920 2922 2932 2934 2940 2942 2968-2970 2988 3072 3095 3097-3101 3136-3138 3140 4223 4303 4307-4310 4312-4314 4323-4326 4328-4330 4351 4373-4375 4377-4380 4387-4390 4392-4394 4400 4415-4416 4435 4444 4451 4457-4458 4460 4495 4499 4501-4506 4508 4515 4528 4544 4575 4595-4598 4601-4603 4629-4631 4633-4636 4645-4647 4651-4652 4654 4656 4687 4693-4695 4700 4708-4710 4713-4716 4736-4738 4755 4757-4758 4761-4764 4771 4780 4800 4831 4845-4847 4850-4854 4856 4864 4917-4919 4921-4924 4933-4935 4937-4940 4944 4960 4997-5002 5008 5459 5477 5489-5494 5499 5585 5587 5621 5623 5629 5679 5761-5765 5768 5786-5787 5800-5802 5804 6391 6395 6459 6461-6463 6477-6479 6481-6483 6497-6499 6535 6539 6717-6719 6753-6755 6757-6759 6797-6799 6801-6803 6817-6819 7507 7516 7786 7823 7829-7830 7838-7839 7841-7843 7882-7883 7886-7887 7898-7899 7902 7924 7926 8074 8112 8114-8115 8118-8120 8122-8123 8172 8174 9179 9181-9183 9191 9193-9197 9200-9202 10237 10239 11261-11263 12247 12252-12254 12271 12273-12276 12280 12282 12287 6/4 521-524 526-527 538 556 640 642 4776-4777 4779 6145 6148-6149 6151 6157 6172-6173 6175 6181 6183 6200-6201 6337 6339 6350-6351 6362-6363 6365-6367 6380-6381 6383 6725 6727 6976-6977 6980-6981 6992-6993 6996-6997 7532-7533 7540 7568-7570 7572-7573 7576 7578-7579 7582-7583 7596-7598 7608-7609 7612-7613 7680-7681 7684-7685 7696-7697 7700-7701 7744 9492 9494-9495 9552-9553 9555 9561 9563 9568 9570 9576 9578 9585 9587 9593 9595 9664 9666 9672 9674 9681 9683 9696 10012-10014 10036 10038 10044 10046 10089 10091 10132 10134 10177 10179 10185 10187 10209 10211 10217 10219 10228-10230 10236 10238 11484 11486 11508 11517 11519 11536 11538 11544 11546 11568 11570 11576 11604 11606 11612 11614 11616-11617 11620-11621 11636 11638 11644 11646 11684-11686 11692 11694 11727 11732 11734 11740 11742 11749 11751 11757 11759 11856-11858 11864 11884 11886 11956 11960 11968-11970 11976 12101 12103 12112-12114 12292 12296 12349 12375 12377-12379 12386-12387 12408-12410 12412 12480-12481 12483-12485 12556-12558 12564 12576-12577 15038-15039 15082-15083 15086-15087 15098-15099 15102 16887 16891 17143 17149-17151 17207 17211 17223 17227 17244-17246 17260-17262 17264-17266 17287 17291 17308-17310 17324-17326 17328-17330 17344-17346 17469-17471 17485-17487 17490-17491 17505-17507 17524 17528 17543 17547 17564-17566 17580-17582 17584-17586 17604 17659 17668-17670 17672-17674 17723 17725-17727 17780 17784 17799 17803 17825-17827 17836-17838 17848 17856-17858 17860 17920-17922 17979 17991 18001-18003 18028-18030 18040 18096-18098 18100 18104 18180 18184 18293-18295 18299 18365-18367 18375 18379 18396-18398 18401-18403 18416-18418 18495 18509-18511 18513-18515 18529-18531 18548 18552 18575 18579 18597-18599 18601-18603 18612-18614 18620 18628 18630 18632-18634 18683 18685-18690 18696 18747 18763 18765-18767 18769-18771 18804 18808 18823 18829-18831 18844-18846 18849-18851 18868 18880-18882 18884 18888 18956 18958 18960 18976-18978 18999 19003 19005-19007 19019 19025-19027 19036-19038 19041-19043 19064 19079 19083 19124 19128 19136-19138 19140 19144 19204 19208 19319 19322-19323 19359 19371 19373-19375 19378-19379 19397-19399 19420 19428-19430 19432-19434 19440 19464 19582-19583 19645-19647 19661-19663 19665-19667 19681-19683 19700 19704 19725-19727 19729-19731 19745-19747 19764 19768 19780 19784 19844 19848 19979 19981-19983 19985-19987 20012-20014 20016-20018 20036 20040 20096-20097 21823 21829-21831 21833-21835 21917 21919 21941 21952-21953 21955 21981-21984 21988 21990-21991 21993 21995 22337 22339 22372-22373 22480-22481 22483 22491 22524-22525 22710-22711 22713-22715 22760 22762-22763 23043 23064-23066 23068 23076-23078 23080 23095 23099 23101-23105 23137-23139 23142 23175 23181-23183 23212-23214 23220 23232-23234 23240 25559 25563 25575 25579 25821-25823 25835 25841-25843 25885-25887 25901-25903 25905-25907 25921-25923 25985-25987 26135 26139 26151 26155 26845-26847 26861-26863 26865-26867 26903 26909-26911 26926 26933 26935 26941-26943 27009-27011 27025-27027 27165 27167 27183 27187 27201-27203 27267 29973 30016 30023 30053 30068 30975 31139 31148 31279 31285-31287 31289-31291 31309-31311 31313-31315 31324 31326 31344-31346 31351 31363 31488 31522-31523 31526-31527 31538-31539 31542 31586-31587 31590 31614 31700 31710 32302-32303 32314-32315 32454 32467 32470 32484 32486 32650-32651 32655 32700 32702 32761-32764 32766-32767 36607 36701-36703 36711 36715 36721-36723 36758-36759 36761-36763 36771 36792-36794 36796 36812-36814 36816-36818 36820 36832 36859 36861-36863 40927 40953-40955 45023 45039 45043 48983 48987 49005-49007 49020-49022 49055 49077-49079 49081 49091 49108 49112 49114 49124-49126 49143 491472.040811542443644e-19 6.090060298487514e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/396/223?format=asciiOpticaldefaultJ/MNRAS/396/223/listList of the stripe filesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFileNameName of the file in subdirectory datameta.id;meta.filecharNqsosNumber of QSOs in the filemeta.numberintStripe[9/86] Stripe numberobs.fieldintFITSGet a FITS copy of the stripemeta.ref.urlcharJ/MNRAS/396/223/qsosQSO candidates in the SDSS stripes examinedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqCandidate IDmeta.idintRAJ2000Right ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainindexedDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainindexedumagPSF magnitude in SDSS/u' bandmagphot.mag;em.opt.UfloatgmagPSF magnitude in SDSS/g' bandmagphot.mag;em.opt.BfloatrmagPSF magnitude in SDSS/r' bandmagphot.mag;em.opt.RfloatimagPSF magnitude in SDSS/i' bandmagphot.mag;em.opt.IfloatzmagPSF magnitude in SDSS/z' bandmagphot.mag;em.opt.Ifloatcl[1,10] Cluster index (generation number of 'goal-successful' cluster)meta.id;stat.fitintStripe[9,86] SDSS Stripe numberobs.fieldintDR7Details from the SDSS-DR7 Photometric Catalog (Cat. II/294)meta.ref.urlcharSloanDisplay the SDSS data for this quasarmeta.ref.urlchar