VII/292ivo://CDS.VizieR/VII/292CDSDuncan K.J.2025-06-18T06:30:49Z2022-09-16T10:16:00ZCDS support team

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

cds-question@unistra.frsurveysredshiftedvisible-astronomyWe present photometric redshift (photo-z) estimates for the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, currently the most sensitive optical survey covering the majority of the extragalactic sky. Our photo-z methodology is based on a machine-learning approach, using sparse Gaussian processes augmented with Gaussian mixture models (GMMs) that allow regions of parameter space to be identified and trained separately in a purely data-driven way. The same GMMs are also used to calculate cost-sensitive learning weights that mitigate biases in the spectroscopic training sample. By design, this approach aims to produce reliable and unbiased predictions for all parts of the parameter space present in wide area surveys. Compared to previous literature estimates using the same underlying photometry, our photo- zs are significantly less biased and more accurate at z>1, with negligible loss in precision or reliability for resolved galaxies at z<1. Our photo-z estimates offer accurate predictions for rare high-value populations within the parent sample, including optically selected quasars at the highest redshifts (z>6), as well as X-ray or radio continuum selected populations across a broad range of flux (densities) and redshift. Deriving photo-z estimates for the full Legacy Imaging Surveys Data Release 8, the catalogues provided in this work offer photo-z estimates predicted to be of high quality for >9x10^8^ galaxies over ~19400deg^2^ and spanning 0<z<7, offering one of the most extensive samples of redshift estimates ever produced.2022MNRAS.512.3662Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/VII/292CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-tohttps://www.legacysurvey.org/dr8 : DESI DR8 Home Pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=VII/292https://vizier.iucaa.in/viz-bin/VizieR-2?-source=VII/292http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=VII/292https://vizier.cds.unistra.fr/viz-bin/votable?-source=VII/292https://vizier.iucaa.in/viz-bin/votable?-source=VII/292http://vizieridia.saao.ac.za/viz-bin/votable?-source=VII/292GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table VII/292/north (Legacy Surveys DR8 North Photometric Redshifts catalog (323 213 867 sources))https://vizier.cds.unistra.fr/viz-bin/conesearch/VII/292/north?https://vizier.iucaa.in/viz-bin/conesearch/VII/292/north?http://vizieridia.saao.ac.za/viz-bin/conesearch/VII/292/north?GETtext/xml+votable180.050000true89.99715297735456.376470386065010.005555555555555556Cone search capability for table VII/292/south (Legacy Surveys DR8 South Photometric Redshifts catalog (1 252 523 992 sources))https://vizier.cds.unistra.fr/viz-bin/conesearch/VII/292/south?https://vizier.iucaa.in/viz-bin/conesearch/VII/292/south?http://vizieridia.saao.ac.za/viz-bin/conesearch/VII/292/south?GETtext/xml+votable180.050000true45.001484297311010.0036550894680.0055555555555555561/4-5 8-10 17 27 35 2/25 28-29 44-46 73-78 101-103 105-107 123 126 133-135 137-139 179-180 3/8 10-11 32 97 99 105 108-109 120-121 124-125 188 190 192-193 196-197 208-209 234-235 238-239 250 260-261 269-271 289-291 316 322 328 341 343 354-355 360 399 403 419 491 510-511 519 523-524 526-527 529-531 544 546-547 639 703 711 724 728 765 767 4/0 2 8 10-11 36 38-39 56 132-134 136-138 384-385 387 393 395 417 419 425 428-429 440-441 443-445 447 488-490 492-493 504-506 508 756-758 764 780-781 792-793 796-797 840-841 930-931 946-947 950-951 994-995 1004 1006-1007 1024-1025 1028-1029 1031 1052-1053 1055 1071 1075 1155 1268-1270 1272-1274 1280 1282-1283 1294 1316 1318 1320-1322 1361 1369 1397 1399 1405 1410-1411 1414-1415 1432 1434 1444-1445 1448 1450 1591 1595 1607 1611 1671 1675 1876-1877 1879 1947 1950 1957-1959 1961-1963 1999 2032 2034-2035 2038-2039 2087 2091 2100-2101 2103 2114-2115 2180-2182 2440 2442 2464 2466 2472 2474 2551 2555 2811 2839 2843 2900-2902 2904-2906 2916-2918 2920-2922 2964-2965 3038-3039 3059 3065 3067 5/4 6 12 14 36 38-39 56 58-59 148 150-151 232 234-235 540-542 556 560-562 576 578 640-642 648 1544-1545 1547 1665 1667 1673 1675 1720-1721 1724-1725 1768-1769 1771 1784-1786 1964-1966 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25509-25511 25663 25678-25679 25687 25690-25691 25698-25699 25743 25747 25763 26687 26703 26707 26723 26772-26773 26775 26779 26791 26794-26795 29968-29969 29971 29981 29983 30049 30161 30966-30967 30970-30971 31118-31119 31130-31131 31138-31139 31178 31216 31218-31219 31221-31223 31279 31283 31285-31287 31310-31311 31362-31363 31365-31367 31882 31910-31911 31921-31923 31962-31963 31972 31974-31975 32160 32162-32163 32172 32174-32175 32186 32532 32540 32542-32543 32577-32579 32582 32600 32602-32603 32605-32607 33130-33131 33133-33135 33138-33139 33141-33143 33175 33179 33190-33191 33195 33201-33203 33365 33367 33369 33371 33383 33385-33387 33430-33431 33433-33435 33445-33447 33449 33451 33632-33633 33635 33802-33803 33809-33811 34936 34938-34939 38925-38927 38945-38947 38962 38968 38970 39056 39058-39059 39064 39066 39088 39090 39096 39098 39440 39442 39472-39474 39480 39482 39568 39570 39600 39602-39603 40791 40793-40795 40805-40807 40809 40811 40853-40855 40857 40859 40871 40877 40879 44906-44907 44910-44911 44924 44926 44949-44951 44953 44955 44965-44967 44969 44971 45397-45399 45402-45403 45413 45415 45417 45419 45461-45463 45466-45467 45477 45479 45481-45483 45654-45655 45658-45659 45688-45689 45691 45812-45813 45815 46452-46453 46456-46457 46516 46520 46532 46536-46538 46716 46772 46776 46788-46789 46792 46794 46800 46852-46854 46880 47188-47189 47191 47197 47368-47369 47371-47374 47384-47385 47412-47413 47415 47464-47465 47467 47476 47480 48132 48134 48136-48137 48511 48565 48567 48573 48589-48591 48595 48919 48923 48935 48941 48943 49029-49031 49036-49037 49039 49061 49063 49069 49071https://cdsarc.cds.unistra.fr/viz-bin/moc/VII/292?format=asciiOpticaldefaultVII/292/northLegacy Surveys DR8 North Photometric Redshifts catalog (323 213 867 sources)idUnique object identifier combining release, brickid and objid (id)meta.id;meta.mainindexedRAJ2000Right Ascension (J2000.0) (ra)degpos.eq.ra;meta.mainindexedDEJ2000Declination (J2000.0) (dec)degpos.eq.dec;meta.mainindexedreleaseLS DR8 release number - denoting the camera and filter set used (release)instr.setup;instr.filterintbrickidLS DR8 brick number (brickid)meta.idintindexedobjidLS DR 8 catalogue object number within this brick (objid)meta.idintindexedtypeOptical morphological model: PSF, REX, DEV, EXP or COMP (type) (1)src.morph.type;meta.modelledcharpstar? Star likelihood based on colours from GMM star-QSO classification (pstar)stat.likelihoodfloatnullablegmmcompBest-matching GMM component used to derive photo-z estimate (gmmcomp)stat.paramcharzphotPhoto-z estimate - mean of the normally distributed photo-z posterior (zphot)src.redshift.photfloate_zphot? Uncertainty on zphot - standard deviation of the normally distributed photo-z posterior (zphot_err)stat.errorfloatnullablefclean? Photometry reliability flag, =1 for sources free of blending or imaging artefacts (flag_clean)meta.codeintnullablefqualPhoto-z reliability flag, =1 for sources expected to have well-constrained estimates and 'flag_clean = 1' (flag_qual)meta.code.qualintVII/292/southLegacy Surveys DR8 South Photometric Redshifts catalog (1 252 523 992 sources)RAJ2000Right Ascension (J2000.0) (ra)degpos.eq.ra;meta.mainindexedidUnique object identifier combining release, brickid and objid (id)meta.id;meta.mainindexedDEJ2000Declination (J2000.0) (dec)degpos.eq.dec;meta.mainindexedreleaseLS DR8 release number - denoting the camera and filter set used (release)instr.setup;instr.filterintbrickidLS DR8 brick number (brickid)meta.idintindexedobjidLS DR 8 catalogue object number within this brick (objid)meta.idintindexedtypeOptical morphological model: PSF, REX, DEV, EXP or COMP (type) (1)src.morph.type;meta.modelledcharpstar? Star likelihood based on colours from GMM star-QSO classification (pstar)stat.likelihoodfloatnullablegmmcompBest-matching GMM component used to derive photo-z estimate (gmmcomp)stat.paramcharzphotPhoto-z estimate - mean of the normally distributed photo-z posterior (zphot)src.redshift.photfloate_zphot? Uncertainty on zphot - standard deviation of the normally distributed photo-z posterior (zphot_err)stat.errorfloatnullablefclean? Photometry reliability flag, =1 for sources free of blending or imaging artefacts (flag_clean)meta.codeintnullablefqualPhoto-z reliability flag, =1 for sources expected to have well-constrained estimates and 'flag_clean = 1' (flag_qual)meta.code.qualint