J/A+A/678/A151ivo://CDS.VizieR/J/A+A/678/A151doi:10.26093/cds/vizier.36780151CDSHardcastle M.J.Horton M.A.Williams W.L.Duncan K.J.Alegre L.,Barkus B.Croston J.H.Dickinson H.Osinga E.Roettgering H.J.A.,Sabater J.Shimwell T.W.Smith D.J.B.Best P.N.Botteon A.Brueggen M.,Drabent A.de Gasperin F.Guerkan G.Hajduk M.Hale C.L.Hoeft M.,Jamrozy M.Kunert-Bajraszewska M.Kondapally R.Magliocchetti M.,Mahatma V.H.Mostert R.I.J.O'Sullivan S.P.Pajdosz-Smierciak U.,Petley J.Pierce J.C.S.Prandoni I.Schwarz D.J.Shulewski A.,Siewert T.M.Stott J.P.Tang H.Vaccari M.Zheng X.Bailey T.,Desbled S.Goyal A.Gonano V.Hanset M.Kurtz W.Lim S.M.Mielle L.,Molloy C.S.Roth R.Terentev I.A.Torres M.2026-08-25T11:31:15Z2023-10-18T08:39:16ZCDS support team

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

cds-question@unistra.frgalaxiescatalogsradio-continuum-emissionradio-sourcesredshiftedvisible-astronomyThe second data release of the LOFAR Two-Metre Sky Survey (LoTSS) covers 27% of the northern sky, with a total area of ~5700deg^2^. The high angular resolution of LOFAR with Dutch baselines (6 arcsec) allows us to carry out optical identifications of a large fraction of the detected radio sources without further radio followup; however, the process is made more challenging by the many extended radio sources found in LOFAR images as a result of its excellent sensitivity to extended structure. In this paper we present source associations and identifications for sources in the second data release based on optical and near-infrared data, using a combination of a likelihood-ratio cross-match method developed for our first data release, our citizen science project Radio Galaxy Zoo: LOFAR, and new approaches to algorithmic optical identification, together with extensive visual inspection by astronomers. We also present spectroscopic or photometric redshifts for a large fraction of the optical identifications. In total 4116934 radio sources lie in the area with good optical data, of which 85% have an optical or infrared identification and 58% have a good redshift estimate. We demonstrate the quality of the dataset by comparing it with earlier optically identified radio surveys. This is by far the largest ever optically identified radio catalogue, and will permit robust statistical studies of star-forming and radio-loud active galaxies.2023A&A...678A.151Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/678/A151CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/659/A1 : LOFAR Two-metre Sky Survey (LoTSS) DR2 (Shimwell+, 2022)http://lofar-surveys.org/dr2_release.html : LOFAR surveys websitehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/678/A151https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/678/A151http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/678/A151https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/678/A151https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/678/A151http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/678/A151GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/678/A151/catalog (Value-added optical identification catalogue for LoTSS DR2)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/678/A151/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/678/A151/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/678/A151/catalog?GETtext/xml+votable180.050000true0.10475027708226.24525822304990.0055555555555555562/21-23 28 38 41-44 3/11 32-34 78-79 83 97 100-101 116 143 147-150 161-163 180 184 208-209 311 315-318 447 511 4/41-43 56 58 140 144 160 303 309-311 325-327 329-331 387 396-397 399 408 412-413 415 468-470 472-474 484-485 565-567 569-571 581-583 586-587 604 624 626 632 634-635 641-643 726 728-730 740-742 744-746 789-791 840-841 843-844 848 936 938-940 1237-1239 1241-1243 1253-1255 1257-1259 1276 1781-1783 1785-1787 2039 2041 2043 5/142-143 161-163 228 230 236 238-239 250 564-566 568-570 580-582 584-586 644-646 648-650 1151 1207 1211 1231 1235 1295 1299 1315 1543 1573 1592-1593 1636-1638 1640 1657 1684 1749 1884 1900 1904 1920-1921 1924-1925 1927 1945 1948 1984 2175 2223 2239 2255 2259 2275 2323 2339 2341-2343 2420 2424 2500 2508 2510 2532 2534-2535 2552 2554 2563 2896 2898-2899 2902 2908 2910 2924 2928 2972 2988 2992 3008 3153-3155 3185 3189 3191 3368-3369 3371 3380-3382 3384-3386 3396-3398 3400-3402 3460-3461 3714 3720 3722-3723 3749-3751 3768 4605-4607 4861-4863 4925-4927 4941-4943 4945-4947 4961-4963 5005-5007 5009-5011 5025-5027 5108-5110 5112-5114 7007 7029-7031 7036-7037 7039 7103 7119 7123 7139 8127 8143 8150-8151 8153-8155 8163 8169-8171 6/618 623 634 638-639 810-811 814 918 924 926 948 950-951 994 2268 2284 2288 2332 2348 2352 2368 2432 2588 2604 2608 2624 2688 4599 4602-4603 4821 4823 4825 4827 4837 4839 4841 4843 4918-4919 4922-4923 4934-4935 4939 5173 5175 5179 5191 5195 5255 5259 6165 6167 6169 6171 6181-6183 6188-6189 6191 6288-6289 6291 6301 6303 6325 6327 6333 6376-6377 6380-6381 6383 6556-6558 6564-6566 6568-6569 6576-6577 6624-6625 6627 6725 6727 6740 6742 6993 7540-7542 7544-7546 7604-7606 7608-7610 7620-7622 7624-7626 7796 7798 7940-7942 7944-7946 8695 8699 8891 8936 8938-8939 8949 8951 8953 8955 9015 9018-9019 9031 9035 9093 9095 9097 9099 9271 9275 9277-9279 9287 9291 9351 9355 9361-9363 9684 9700 9704 10004 10008 10010-10011 10014 10036 10038 10044 10132 10134-10135 10184 10186 10212 10214 10220 10222 10247 10251 11588 11590-11591 11614 11636 11638 11700-11702 11704-11706 11708 11716-11718 11720-11722 11728 11892-11894 11896-11898 11956-11958 11960-11962 11972-11974 11976-11978 12036-12038 12040-12042 12044 12048 12573 12575 12597 12599 12737 12752-12753 12755 12761 12763 12788-12789 12791 13480-13481 13483 13532 13548 13552 13596 13612 13616 13632 13696 13828-13829 13831 13849 13852 13888 14884 14886-14887 14899 14904-14906 14909-14911 14954-14955 14958-14959 14993-14995 15056 15058 15064 15076 15080 19421-19423 19437-19439 19441-19443 19679 19694-19695 19699 19743 19759 19763 19843 19999 20014-20015 20018-20019 20034-20035 20099 20444 20460 20464 28023 28027 28103 28109 28111 28113-28115 28133 28153-28155 28407 28411 28470-28471 28474-28475 28486-28487 28491 28551 28555 32507 32591 32595 32598-32599 32610-32611 32673-32675https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/678/A151?format=asciiOpticalRadiodefaultJ/A+A/678/A151/catalogValue-added optical identification catalogue for LoTSS DR2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Radio right ascension (mean position) (J2000) (RA)degpos.eq.ra;meta.mainindexedAssocNumber of components used to form composite source (Assoc)meta.numberintIDQual? Quality of association from RGZ(L) (ID_Qual)meta.code.qualdoublenullablepstar[0/1]? Star likelihood based on GMM modelling (type='PSF' sources only) (pstar)stat.likelihooddoublenullableStar[True-False ] Likely star based on pstar or proper motion (deprecated), blank if no match (star)meta.codecharGMMcompGaussian Mixture Model component to which source belongs (and hence the gpz++ class used for prediction) (gmmcomp)meta.codecharzphot[-3.73/8.28]? Photo-z estimate (zphot)src.redshift.photdoublenullablezspecSDSS[-0.01/5]? SDSS spectroscopic redshift if available (zspec_sdss)src.redshift;pos.heliocentricdoublenullableResolved[0/1] Boolean flag to indicate whether source is resolved (Resolved)meta.codeintfLMflux[0/1] Flag to say that LoMorph flux is bad (Bad_LM_flux)meta.codeintr50? Half-light radius of Legacy optical exponential/DeVaucouleurs/composite model (r_50)arcsecphys.angSize;srcdoublenullablee_r50? 1-sigma uncertainty on r_50 (r_50_err)arcsecstat.errordoublenullableq_logMass[0/1] 1 if a mass is measured and reliable (flag_mass)meta.code.qual;phys.massintSourceObject identifier (ILT name) (Source_Name)meta.id;meta.maincharindexedDEJ2000Radio declination (mean position) (J2000) (DEC)degpos.eq.dec;meta.mainindexede_RAJ2000Error on radio right ascension (E_RA)arcsecstat.error;pos.eq.radoublee_DEJ2000Error on radio declination (E_DEC)arcsecstat.error;pos.eq.decdoubleFtot144-MHz total flux density (Total_flux)mJyphot.flux.density;em.radio.100-200MHzdoublee_FtotError on total flux density (E_Total_flux)mJystat.errordoubleFpeak144-MHz peak flux density (Peak_flux)mJy/beamphot.flux.density;em.radio.100-200MHzdoublee_FpeakError on peak flux density (E_Peak_flux)mJy/beamstat.errordoubleSCode[SCMZ] PyBDSF source code or Z for composite source (S_Code) (1)meta.codecharMosaicIDLoTSS mosaic of source image (Mosaic_ID)obs.imagecharMaj? Major axis of fitted Gaussian (Maj)arcsecphys.angSize;meta.modelleddoublenullableMin? Minor axis of fitted Gaussian (Min)arcsecphys.angSize;srcdoublenullablePA? Position angle of fitted Gaussian (PA)degpos.posAng;meta.modelleddoublenullablee_Maj? Error on major axis (E_Maj)arcsecstat.errordoublenullablee_Min? Error on minor axis (E_Min)arcsecstat.error;stat.mindoublenullablee_PA? Error on position angle (E_PA)degstat.errordoublenullableXMMSL2ID in XMM source catalogue (XMMSL2_ID)meta.idcharDCMaj? Deconvolved major axis of fitted Gaussian (DC_Maj)arcsecphys.angSize.smajAxisdoublenullableDCMin? Deconvolved minor axis of fitted Gaussian (DC_Min)arcsecphys.angSize.sminAxisdoublenullableDCPA? Deconvolved position angle of fitted Gaussian (DC_PA)degpos.posAng;meta.modelleddoublenullableIslrmsrms noise in island (Isl_rms)mJy/beamstat.stdev;instr.det.noisedoubleFlagW[-1/23] Flag for workflow status (internal) (FLAG_WORKFLOW)meta.code.errorintIDFlag[-99/14]? Flag for workflow status (internal) (ID_flag) (2)meta.codeintnullablePreFilt[-99/14] Prefilter status (internal) (Prefilter) (2)meta.codeintPostFilt[0/6] Postfilter status (internal) (Postfilter)meta.codeintlikefin? Final likelihood ratio value (internal) (lr_fin)stat.likelihooddoublenullableRAOdeg? Optical right ascension (J2000) (see r_RAOdeg) (optRA)degpos.eq.ranullableDEOdeg? Optical declination (J2000) (see r_RAOdeg) (optDec)degpos.eq.decnullableCompSize? Max size of convex hull surrounding components for composite sources (Composite_Size)arcsecphys.angSize;srcdoublenullableCompWidth? Transverse size of convex hull surrounding components for composite sources (Composite_Width)arcsecphys.angSize;srcdoublenullableCompPA? Position angle on the sky of longest axis of convex hull (Composite_PA)degpos.posAng;obs.fielddoublenullableAssocQual? Quality of association from RGZ(L) (Assoc_Qual)meta.code.qualdoublenullableBlendProb? Blend probability from RGZ(L) or manual flagging) (Blend_prob)stat.fit.goodnessdoublenullableOtherProb? Other problem probability from RGZ(L) (Other_prob)stat.fit.goodnessdoublenullabler_RAOdegOrigin of optRA, optDec (Position_from)meta.ref;pos.framecharRenamedOriginal name e.g. in RGZ if a composite source (Renamed_from)meta.idcharRAIdeg? Right ascension (J2000) of positional match in Legacy/WISE crossmatch catalogue (ID_RA)degpos.eq.ranullableDEIdeg? Declination (J2000) of positional match in Legacy/WISE crossmatch catalogue (ID_DEC)degpos.eq.decnullableUIDL? Legacy ID if any (UID_L)meta.idcharUNWISEUNWISE ID if any (UNWISE_OBJID)meta.idcharIDNameLegacy ID if present else WISE ID else blank if no ID exists (ID_NAME)meta.idcharSep? Offset between optRA, optDec and ID_RA, ID_DEC (non-zero only for visual inspection) (Separation)pos.angDistancedoublenullableLegacyID? Unique source ID combining release, brick ID and objid (Legacy_ID)meta.idnullableHPX[16/303] Healpix of Legacy brick (internal) (HPX)stat.fit.paramintRelease[8000/8001]? Legacy release number (release)meta.idintnullableBrickId[422713/641534]? Legacy brick ID (brickid)meta.idintnullableObjId? Legacy object ID (objid)meta.idintnullableMaskbits? Bitwise mask indicating that an object touches a pixel in the `coadd/*/*/*maskbits*` maps, as catalogued on the DR8 bitmasks page (maskbits)meta.noteintnullablefracFg? Profile-weighted fraction of the flux from other sources divided by the total flux in g (fracflux_g)phot.flux;arith.ratiodoublenullablefracFr? Profile-weighted fraction of the flux from other sources divided by the total flux in r (fracflux_r)phot.flux;arith.ratiodoublenullablefracFz? Profile-weighted fraction of the flux from other sources divided by the total flux in z (fracflux_z)phot.flux;arith.ratiodoublenullableTypeMorphological model (type) (3)src.morph.type;meta.modelledcharRALdeg? Right ascension (J2000) of match in Legacy catalogue (ra)degpos.eq.ranullableDELdeg? Declination (J2000) of match in Legacy catalogue (dec)degpos.eq.decnullablee_zphot[-0.01/7.6]? Predicted 1-sigma uncertainty on photometric redshift (after magnitude calibration) (zphot_err)stat.errordoublenullablevarDensity[0.0/1.22]? gpz++ predicted variance from density of training set (var.density)stat.variancedoublenullablevarTrNoise[0.0/66.83]? gpz++ predicted variance from noise in training set (var.tr.noise)stat.variancedoublenullablevarInNoise[0.0/3.89]? gpz++ predicted variance from noise in fluxes used in prediction (var.in.noise)stat.variancedoublenullableFlagQual[0/1]? Predicted photo-z quality flag, 0 if bad, 1 if good (flag_qual) (4)meta.code.errorintnullablezwarnSDSS? 0 if SDSS redshift is good, 1 if bad (zwarning_sdss)meta.codeintnullablePlateSDSS? SDSS plate number (plate_sdss)meta.idintnullableMJDSDSS? SDSS MJD (mjd_sdss)meta.idintnullableFiberSDSS? SDSS fibre ID (fiberid_sdss)meta.idintnullablezHETDEX[0.01/4.15]? HETDEX spectroscopic redshift if available (z_hetdex)src.redshift;pos.heliocentricdoublenullablezHETDEXConf? HETDEX spectroscopic redshift confidence (z_hetdex_conf)stat.fit.goodnessdoublenullableHETDEX? HETDEX source ID (hetdex_sourceid)meta.idnullablezDESI[-0.01/4.84]? DESI spectroscopic redshift if available (z_desi)src.redshift;pos.heliocentricdoublenullablee_zDESI[0.0/0.01]? DESI spectroscopic redshift error (z_desi_err)stat.errordoublenullableDESI? DESI source ID (desi_sourceid)meta.idnullable2RXSID in 2RXS (2RXS_ID)meta.idcharLASEstimate of angular size, only valid for sources with Resolved==True (LAS)arcsecphys.angSizedoublezbest[0/6.6]? Spec-z if available and good, else photo-z if available and good, else blank (z_best) (5)src.redshift;pos.heliocentricdoublenullabler_zbestString describing origin of z_best (z_source)meta.ref;pos.framecharSize? LAS times angular size distance (Size)kpcphys.size.diameterdoublenullableL144? Radio luminosity at 144MHz for alpha=0.7 (L_144) (6)W/Hzphys.luminosity;em.radio.100-200MHzdoublenullableFieldWhich of the two fields the data come from (Field)obs.fieldcharLegacyCovFlag to say whether source is in the DESI Legacy sky area (Legacy_Coverage)meta.codeintLMFluxFlux density from LoMorph code (LM_flux)mJyphot.flux.densitydoubleLMSize? Size from LoMorph code (LM_size)arcsecphys.size.diameterdoublenullablefLMimage[0/1] Flag to say that LoMorph mask is bad (Bad_LM_image)meta.codeintr_LASSource for the LAS column (LAS_from)meta.ref;pos.framechargmag? Magnitude in g-band (mag_g)magphot.mag;em.opt.Bdoublenullablee_gmag? Magnitude error in g-band, or blank for upper limit (magerr_g)magstat.error;phot.magdoublenullablermag? Magnitude in r-band (mag_r)magphot.mag;em.opt.Rdoublenullablee_rmag? Magnitude error in r-band, or blank for upper limit (magerr_r)magstat.error;phot.magdoublenullablezmag? Magnitude in z-band (mag_z)magphot.mag;em.opt.Idoublenullablee_zmag? Magnitude error in z-band, or blank for upper limit (magerr_z)magstat.error;phot.magdoublenullableW1mag? Magnitude in WISE band 1 (mag_w1)magphot.mag;em.IR.3-4umdoublenullablee_W1mag? Magnitude error in WISE band 1, or blank for upper limit (magerr_w1)magstat.error;phot.magdoublenullableW2mag? Magnitude in WISE band 2 (mag_w2)magphot.mag;em.IR.4-8umdoublenullablee_W2mag? Magnitude error in WISE band 2, or blank for upper limit (magerr_w2)magstat.error;phot.magdoublenullableW3mag? Magnitude in WISE band 3 (mag_w3)magphot.flux.density;em.IR.8-15umdoublenullablee_W3mag? Magnitude error in WISE band 3, or blank for upper limit (magerr_w3)magstat.error;phot.magdoublenullableW4mag? Magnitude in WISE band 4 (mag_w4)magphot.flux.density;em.IR.15-30umdoublenullablee_W4mag? Magnitude error in WISE band 4, or blank for upper limit (magerr_w4)magstat.error;phot.magdoublenullabler_WISEOrigin of the WISE measurements (WISE_Src) (3)meta.ref;pos.framecharlogMass? Source host galaxy stellar mass estimate estimate (Mass_median)log(solMass)phys.massdoublenullableb_logMass? 68% lower confidence bound on mass (Mass_l68)log(solMass)phys.massdoublenullableB_logMass? 68% upper confidence bound on mass (Mass_u68)log(solMass)phys.massdoublenullablegmagrest? Rest-frame g-band magnitude from SED fit (g_rest)magphot.mag;meta.modelleddoublenullablermagrest? Rest-frame r-band magnitude from SED fit (r_rest)magphot.mag;meta.modelleddoublenullablezmagrest? Rest-frame z-band magnitude from SED fit (z_rest)magphot.mag;meta.modelleddoublenullableUmagrest? Rest-frame U-band magnitude from SED fit (U_rest)magphot.mag;em.opt.UdoublenullableVmagrest? Rest-frame V-band magnitude from SED fit (V_rest)magphot.mag;em.opt.VdoublenullableJmagrest? Rest-frame J-band magnitude from SED fit (J_rest)magphot.mag;em.IR.JdoublenullableKmagrest? Rest-frame K-band magnitude from SED fit (K_rest)magphot.mag;em.IR.KdoublenullableW1magrest? Rest-frame WISE band-1 magnitude from SED fit (w1_rest)magphot.mag;em.IR.KdoublenullableW2magrest? Rest-frame WISE band-1 magnitude from SED fit (w2_rest)magphot.mag;meta.modelleddoublenullableCreatedOrigin of radio component assignment (Created)meta.codecharMaskOpt[True-False ] Bitwise mask set if the central pixel from any image satisfies each condition in any of g, r or z as catalogued on the DR8 bitmasks page (ANYMASK_OPT)meta.codechar