J/A+A/545/A68ivo://CDS.VizieR/J/A+A/545/A68doi:10.26093/cds/vizier.35450068CDSFumagalli M.Furniss A.O'Meara J.Prochaska J.X.Williams D.Farina E.2017-07-04T07:08:41Z2012-09-10T08:42:57ZCDS support team

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

cds-question@unistra.frbl-lacertae-objectsspectroscopyPKS 0447-439 is one of the BL Lacertae objects that have been detected at very high energy. There has been a recent report of a lower limit of z>=1.246 for the redshift of this blazar, challenging the current paradigm in which very high-energy {gamma}-rays cannot freely propagate in the z>~1 universe. In this research note, we present a new MagE/Magellan spectrum of PKS 0447-439 with exquisite signal-to-noise (S/N>150 at 6500{AA}). Our analysis confirms the presence of the previously-reported absorption line at 6280{AA}, which we identify, however, with a known telluric absorption, invalidating the claim that this blazar lies at z>1. Since no other extragalactic spectral features are detected, we cannot establish a redshift based on our spectrum.2012A&A...545A..68Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/545/A68CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/545/A68https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/545/A68http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/545/A68https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/545/A68https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/545/A68http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/545/A68GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/545/A68/spectrumOptical spectrum of the blazar PKS 0447-439recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3500.1/8101] Observed wavelength0.1nmem.wldoubleFluxFlux (10^-16^erg/cm^2^/s/{AA})aW.m**-2.nm**-1phot.flux.density;em.optdoublee_Flux1 sigma error on Flux (10^-16^erg/cm^2^/s/{AA})aW.m**-2.nm**-1stat.error;phot.fluxdouble