J/A+A/587/A112ivo://CDS.VizieR/J/A+A/587/A112doi:10.26093/cds/vizier.35870112CDSTaris F.Andrei J.Roland A.Klotz A.Vachier S.Souchay J.2017-10-11T05:13:45Z2016-02-26T08:46:41ZCDS support team

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

cds-question@unistra.frquasarsactive-galactic-nucleiapparent-magnitudeThe Gaia astrometric mission of the European Space Agency was launched on December 2013. It will provide a catalog of 500 000 quasars. Some of these targets will be chosen to build an optical reference system that will be linked to the International Celestial Reference Frame (ICRF). The astrometric coordinates of these sources will have roughly the same uncertainty at both optical and radio wavelengths, and it is then mandatory to observe a common set of targets to build the link. In the ICRF, some targets have been chosen because of their pointlikeness. They are quoted as defining sources, and they ensure very good uncertainty about their astrometric coordinates. At optical wavelengths, a comparable uncertainty could be achieved for targets that do not exhibit strong astrophysical phenomena, which is a potential source of photocenter flickering. A signature of these phenomena is a magnitude variation at optical wavelengths. The goal of this work is to present the time series of 14 targets suitable for the link between the ICRF and the future Gaia Celestial Reference Frame. The observations have been done systematically by robotic telescopes in France and Chile once every two nights since 2011 and in two filters. These time series are analyzed to search for periodic or quasi-periodic phenomena that must be taken into account when computing the uncertainty about the astrometric coordinates. Two independent methods were used in this work to analyze the time series. We used the CLEAN algorithm to compare the frequency obtained to those given by the Lomb-Scargle method. It avoids misinterpreting the frequency peaks given in the periodograms.2016A&A...587A.112Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/587/A112CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/587/A112https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/587/A112http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/587/A112https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/587/A112https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/587/A112http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/587/A112GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/587/A112/sources (Studied sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/587/A112/sources?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/587/A112/sources?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/587/A112/sources?GETtext/xml+votable180.050000true2.6291911110.974861940.0055555555555555566/5306 7896 8915 19271 19567 19831 22659 28454 28517 32261 38383 40479 45409 470142.762881831355591e-19 3.9105737390043815e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/587/A112?format=asciidefaultJ/A+A/587/A112/table5List of observations in R filter from 2011 to 2015recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTargetTarget name, BHHMM+DDd-F-OOO (1)meta.id;meta.maincharJDJulian date of observationtime.epochdoublemagMagnitude in Filterphot.magfloatrmsUncertainty of the magnitude determinationstat.errorfloatFilt[RV] Filter (V or R Cousins)meta.id;instr.filtercharObsObservatory code (ESO or OCA)meta.code;instr.obstycharJ/A+A/587/A112/table6List of observations in V filter from 2011 to 2015Filt[RV] Filter (V or R Cousins)meta.id;instr.filtercharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTargetTarget name, BHHMM+DDd-F-OOO (1)meta.id;meta.maincharJDJulian date of observationtime.epochdoublemagMagnitude in Filterphot.magfloatrmsUncertainty of the magnitude determinationstat.errorfloatObsObservatory code (ESO or OCA)meta.code;instr.obstycharJ/A+A/587/A112/sourcesStudied sourcesMTypeObject typesrc.classcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameIERS name (BHHMM-DDd)meta.id;meta.maincharRAJ2000LQAC2 right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000LQAC2 declination (J2000)degpos.eq.dec;meta.main<Rmag>Average Cousins R magnitudemagphot.mag;em.opt.Rfloate_<Rmag>rms uncertainty on <Rmag>magstat.error;phot.mag;em.opt.Rfloat<Vmag>Average Cousins V magnitudemagphot.mag;em.opt.Vfloate_<Vmag>rms uncertainty on <Vmag>magstat.error;phot.mag;em.opt.VfloatzRedshiftsrc.redshiftdoubleLCShow the V and R light curvesmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlchar