J/AJ/143/145ivo://CDS.VizieR/J/AJ/143/145doi:10.26093/cds/vizier.51430145CDSKellar J.A.Salzer J.J.Wegner G.Gronwall C.Williams A.2017-06-21T08:22:00Z2013-07-30T10:11:29ZCDS support team

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

cds-question@unistra.frspectroscopyredshiftedseyfert-galaxiesquasarsmetallicityline-intensitiesDuring a wide-field narrowband H{alpha} imaging survey, we noted the presence of numerous isolated emission-line point sources in the data. These objects could represent ultra-low-luminosity galaxies at low-redshift (detection via H{alpha}), isolated extragalactic HII regions associated with the galaxy targeted by the original observation, or background galaxies or QSOs where strong emission lines (most often [OIII]{lambda}5007) redshift into our narrowband filter. We have carried out a systematic search for these "H{alpha} dots" in over 200 15x15arcmin fields. To date we have cataloged 61 candidate emission-line sources in roughly 11.7deg^2^. The sample has a median R magnitude of 19.5, and detects objects as faint as R=22.6. Follow-up spectroscopy reveals that ~85% of the candidates are bona fide emission-line objects, with roughly 60% of the real sources being lower-redshift objects (detection via H{alpha}) and 40% being higher-redshift objects detected via [OIII] emission or some other emission line. Here we present the results of our initial survey and follow-up spectroscopy. We use our sample to study the properties (including star-formation rates and metal abundances) of low-luminosity star-forming galaxies in the nearby universe and of low-metallicity star-forming galaxies at z~0.33.2012AJ....143..145Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/143/145CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/77 : HI spectral properties of galaxies (Springob+, 2005)J/AJ/143/133 : Properties of dwarf galaxies from the ALFALFA surveyJ/A+A/545/A16 : Halpha3. Catalog and SFR in Virgo cluster (Gavazzi+, 2012)J/AJ/142/170 : ALFALFA survey: the {alpha}.40 HI source catalogJ/AJ/139/279 : Outlying HII regions in HI-selected galaxies (Werk+, 2010)J/AJ/138/338 : Arecibo Legacy Fast ALFA Survey. IX. (Stierwalt+, 2009)J/ApJS/178/247 : H{alpha} and [NII] survey in local 11Mpc (Kennicutt+, 2008)J/ApJS/173/538 : XUV-Disk galaxies in the Local Universe (Thilker+, 2007)J/ApJ/668/853 : Spectroscopy of UltraStrong Emission Line galaxiesJ/ApJS/165/307 : Survey for ionization in neutral gas galaxies. I.J/AJ/130/2571 : KISS H{alpha}-selected survey list 3 (Jangren+, 2005)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/143/145https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/143/145http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/143/145https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/143/145https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/143/145http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/143/145GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/143/145/Ha_dot (H{alpha} dot candidates-observed properties, spectroscopic results and derived quantities)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/143/145/Ha_dot?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/143/145/Ha_dot?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/143/145/Ha_dot?GETtext/xml+votable180.050000true131.78541710.1767220.0055555555555555566/732 734 904 905 908 2121 2122 2123 4252 8714 8724 8744 19923 19943 19954 19955 19958 19960 19961 19964 20209 20215 20217 20358 27513 27580 27589 27757 27771 27837 27855 27909 27921 27940 28225 31670 31673 31678 31688 31689https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/143/145?format=asciiOpticaldefaultJ/AJ/143/145/Ha_dotH{alpha} dot candidates-observed properties, spectroscopic results and derived quantitiescHb? Decimal reddening coefficient c_H{beta}_, derived from the Balmer-line ratio H{alpha}/H{beta}phot.color.excessfloatnullableW(Ha)? Equivalent width of the H{alpha} line0.1nmspect.line.eqWidthfloatnullableW(O3)? Equivalent width of the [OIII] line0.1nmspect.line.eqWidthfloatnullablelog(N2/Ha)? Key reddening-corrected emission-line ratio log([NII]{lambda}6583/H{alpha})(4)spect.line.intensity;arith.ratiofloatnullablef_log(N2/Ha)[*] Unreliable log([NII]/Ha) (5)meta.codecharlog(O3/Hb)? Key reddening-corrected emission-line ratio log([OIII]{lambda}5007/H{beta})(4)spect.line.intensity;arith.ratiofloatnullablef_log(O3/Hb)[*] Unreliable log([OIII]/Hb) (5)meta.codecharlog(O2/Hb)? Key reddening-corrected emission-line ratio log([OII]{lambda}3727/H{beta}) (4)spect.line.intensity;arith.ratiofloatnullablef_log(O2/Hb)[*] Unreliable log([OII]/Hb) (5)meta.codecharlog(S2/Ha)? Key reddening-corrected emission-line ratio log([SII]{lambda}{lambda}6717, 6731/H{alpha}) (4)spect.line.intensity;arith.ratiofloatnullablef_log(S2/Ha)[*] Unreliable log([SII]/Ha) (5)meta.codechar[O/H]? Metallicity (log(O/H)+12) (see Section 6.2)log(Sun)phys.abundfloatnullableDistDistanceMpcpos.distance;pos.heliocentricfloatnullableRMag? Absolute R magnitudemagphot.mag;em.opt.Rfloatnullablelog(LHa)? The H{alpha} luminosity log(L_H{alpha}_) (in erg/s) (6)log(1e-07W)phys.luminosity;em.line.HalphafloatnullableSFR? Star-formation rate (7)solMass/yrphys.SFRfloatnullableDV? Velocity difference (8)km/sphys.veloc;arith.diffintnullableDR? Physical separation distance (8)Mpcpos.distancefloatnullableSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDot[1/61] H{alpha} dot candidate number <[KSW2012] NNN> in Simbad (G1)meta.id;meta.mainintf_Dot[s] Multiple detections (G2)meta.codecharRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainDmagDifference between the instrumental R and H{alpha} magnitudes (1)magphot.mag;em.line.HalphafloatRatioRatio of the magnitude difference Dmag to the magnitude difference error (2)stat.fit.goodnessfloatFluxThe measured emission-line flux as measured from the continuum-subtracted narrowband images (in 10^-14^erg/s/cm^2^)1e-17W.m**-2phot.fluxfloate_FluxError in Flux (in 10^-14^erg/s/cm^2^)1e-17W.m**-2stat.error;phot.fluxfloatRmag[15.83/22.64] The measured broadband R magnitude; VEGA systemmagphot.mag;em.opt.Rfloate_RmagError in Rmagmagstat.error;phot.mag;em.opt.RfloatELGEmission-line galaxy type (3)src.classcharz? Spectroscopic redshift, derived from the average redshift all strong emission lines (typical uncertainties are 15-30km/s)src.redshiftfloatnullable