J/ApJS/254/26ivo://CDS.VizieR/J/ApJS/254/26doi:10.26093/cds/vizier.22540026CDSRajagopal M.Marchesi S.Kaur A.Dominguez A.Silver R.Ajello M.2022-01-19T12:35:09Z2021-09-16T16:20:43ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleivisible-astronomyspectroscopygamma-ray-astronomyastronomical-object-identificationAs a follow-up to the optical spectroscopic campaign aimed at achieving completeness in the Third Catalog of Hard Fermi-LAT Sources (3FHL), we present here the results of a sample of 28 blazars of an uncertain type observed using the 4m telescope at Cerro Tololo Inter-American Observatory in Chile. Out of these 28 sources, we find that 25 are BL Lacertae objects (BL Lacs) and 3 are flat-spectrum radio quasars (FSRQs). We measure redshifts or lower limits for 16 of these blazars, and it is observed that the 12 remaining blazars have featureless optical spectra. These results are part of a more extended optical spectroscopy follow-up campaign for 3FHL blazars, where, until now, 51 blazars of an uncertain type have been classified into BL Lac and FSRQ categories. Furthermore, this campaign has resulted in redshift measurements and lower limits for 15 of these sources. Our results contribute toward attaining a complete sample of blazars above 10 GeV, which then will be crucial in extending our knowledge on blazar emission mechanisms and the extragalactic background light.2021ApJS..254...26Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/254/26CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)J/A+A/495/691 : Multifrequency catalog of blazars, Roma-BZCAT (Massaro+, 2009)J/A+A/538/A26 : BL Lac objects beyond z=1.3 (Rau+, 2012)J/ApJ/748/49 : Optical spectroscopy of 1LAC broad-line blazars (Shaw+, 2012)J/ApJ/764/135 : Spectroscopic redshifts of BL Lac objects (Shaw+, 2013)J/ApJ/780/73 : Redshifts of BL Lac objects from Fermi (Ajello+, 2014)J/A+A/579/A34 : 1WHSP: VHE {gamma}-ray blazar candidates (Arsioli+, 2015)J/ApJS/232/18 : The third Fermi-LAT >10GeV catalog (3FHL) (Ajello+, 2017)J/A+A/598/A17 : The 2WHSP catalog (Chang+, 2017)J/ApJS/233/3 : VLBA Extragalactic Proper Motion Catalog (Truebenbach+, 2017)J/ApJS/247/33 : The Fermi LAT fourth source catalog (4FGL) (Abdollahi+, 2020)J/A+A/643/A103 : Fermi-LAT sources low-energy counterparts (Pena-Herazo+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/254/26https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/254/26http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/254/26https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/254/26https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/254/26http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/254/26GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/254/26/table1 (List of sources and their properties sorted in the order of increasing R.A. values)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/254/26/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/254/26/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/254/26/table1?GETtext/xml+votable180.050000true0.3877083-41.92341940.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/ApJS/254/266/16740 20861 24641 24737 29126 35498 36910 36973 37523 38316 41155 41325 41966 41970 42571 42920 43085 43443 43996 44290 44902 45632 45820 46564 47497 48090 48778 48933https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/254/26?format=asciiGamma-rayOpticaldefaultJ/ApJS/254/26/table1List of sources and their properties sorted in the order of increasing R.A. valuesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint3FHL3FHL source name (JHHMM.m+DDMM)meta.id;meta.maincharCNameOptical, IR, X-ray or radio counterpart namespect.dopplerVeloc.optcharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainE(B-V)[0.01/0.78] Reddening (1)magphot.color.excessfloatVmag[15.38/20.21] V-band magnitude (AB system)magphot.mag;em.opt.VfloatDateDate of observation (UT)time.epochnullableExp[900/6200] Exposure time of the source under considerationstime.duration;obs.exposureintSlope[-4.92/1.6] Slope of the continuum fit obtained from the observed spectrastat.fit.paramfloatfitsDownload the FITS filemeta.ref.urlcharFileNameName of the file in subdirectory "sp/"; column added by CDSmeta.id;meta.filecharspInteractive plot of the spectrummeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharNEDNED column added by the CDSmeta.ref.urlchar