J/ApJS/257/41ivo://CDS.VizieR/J/ApJS/257/41doi:10.26093/cds/vizier.22570041CDSKalita N.Gupta A.C.Gu M.2022-09-07T13:02:21Z2022-04-05T15:26:36ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleibl-lacertae-objectsquasarsinfrared-photometryvisible-astronomybroad-band-photometryx-ray-sourcesredshiftedIn an optical monitoring program to characterize the variability properties of blazars, we observed 10 sources from the Roma-BZCAT catalog for 26 nights in V and R bands during 2014 October to 2015 June with two telescopes located in India. The sample includes mainly newly discovered BL Lacertae objects (BL Lacs) for which the redshift of some sources is not yet known. We present the results of flux and color variations of the sample on intraday and short timescales obtained by using the power-enhanced F-test and the nested-ANOVA tests, along with their spectral behavior. We find significant intraday variability in the single flat-spectrum radio quasar in our sample, having an amplitude of variation ~12%. Although a few of the BL Lacs showed probable variation in some nights, none of them passed the variability tests at 99.9% significance level. We find that 78% of the sample showed significant negative color-magnitude correlations, i.e., a redder-when-brighter spectral evolution. Those that do not show strong or clear chromatism predominantly exhibit a redder-when-brighter trend. Unlike on hourly timescales, the high- synchrotron-peaked blazars in the sample (BZGJ0656+4237, BZGJ0152+0147, and BZBJ1728+5013) show strong flux variation on timescales of days to months, where again we detect a decreasing trend of the spectral slope with brightness. We observe a global steepening of the optical spectrum with increasing flux on the intranight timescale for the entire blazar sample. The nonvariability in the BL Lacs in our sample might be caused by the distinct contribution from the disk as well as from other components in the studied energy range.2021ApJS..257...41Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/257/41CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)J/A+A/327/61 : BV(RI)c photometry of S5 0716+714 (Ghisellini+ 1997)J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)J/ApJ/537/101 : Optical Study for blazars. I. (Fan+, 2000)J/A+A/495/691 : Multifrequency cat. of blazars, Roma-BZCAT (Massaro+, 2009)J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)J/ApJ/744/177 : VLBA 5GHz observations of Fermi/LAT AGNs (Linford+, 2012)J/MNRAS/421/1861 : OJ287 polarization and VLBI jet direction (Valtonen+, 2012)J/A+A/560/A23 : Radio properties of faint BL Lacs (Liuzzo+, 2013)J/A+A/570/A126 : XShooter spectrum of 4 BL Lacs (Landoni+, 2014)J/ApJS/226/20 : X-ray, opt. & radio SEDs of Fermi blazars (Fan+, 2016)J/A+A/608/A68 : TeV BL Lacs multi-lambda fluxes (Fallah Ramazani+, 2017)J/ApJS/229/21 : VRI monitoring of the QSO 3C 273 in 2005-2016 (Xiong+, 2017)J/ApJ/880/155 : RI photometry of blazars S5 0716+714 and 3C 273 (Liu+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/257/41https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/257/41http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/257/41https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/257/41https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/257/41http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/257/41GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/257/41/table2 (Basic parameters of the Roma-BZCAT catalog blazars studied in our sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/257/41/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/257/41/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/257/41/table2?GETtext/xml+votable180.050000true28.1645831.7880830.0055555555555555566/6534 6764 7311 7716 9711 17843 23015 26292 27851 322612.762881831355591e-19 3.3785437584409506e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/257/41?format=asciiX-rayOpticalInfrareddefaultJ/ApJS/257/41/table2Basic parameters of the Roma-BZCAT catalog blazars studied in our sampleSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource name, BZCAT catalog (<[MGL2009] BZ{BQ} JHHMM+DDMM> or <[MML2015] 5BZG JHHMM+DDMM> in Simbad)meta.id;meta.maincharprimaryONameOther name from the Fermi-AGN catalogmeta.idcharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainz[0.041/0.158]? Redshiftsrc.redshiftfloatnullableRmag[11.1/15.7] Apparent R-band magnitude from BZCATmagphot.mag;em.opt.RfloatClassObject classmeta.code.classcharTypeSource type based on SED (1)src.classcharFx[0.44/63.1]? 0.1-2.4keV X-ray flux in units of 10^-12^erg/cm^2^/s1e-15W.m**-2phot.flux;em.X-rayfloatnullableNrNumber of R-band measurements for this blazarmeta.numberintnullableNvNumber of V-band measurements for this blazarmeta.numberintnullableLCLight curves interactive plotmeta.ref.urlcharJ/ApJS/257/41/fig1vDifferential V-band magnitude light curvesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Date of observationdtime.epochdoubledVmag1[-0.55/1.25] Differential V band magnitude, source-reference starmagphot.mag;arith.diffdoublee_dVmag1[0.002/0.031] Uncertainty in dVmag1magstat.error;phot.magdoubledVmag2[-0.76/2.27] Differential V band magnitude, comparison star 1 - reference starmagphot.mag;arith.diffdoublee_dVmag2[0.0027/0.042] Uncertainty in dVmag2magstat.error;phot.magdoubleNameSource name as in Table 2meta.id;meta.maincharJ/ApJS/257/41/fig1rDifferential R-band magnitude light curvesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource name as in Table 2meta.id;meta.maincharJDJulian Date of observationdtime.epochdoubledRmag1[-0.33/0.91] Differential R band magnitude, source-reference starmagphot.mag;arith.diffdoublee_dRmag1[0.0018/0.031] Uncertainty in dRmag1magstat.error;phot.magdoubledRmag2[-0.54/1.95] Differential R band magnitude, comparison star 1 - reference starmagphot.mag;arith.diffdoublee_dRmag2[0.0024/0.043] Uncertainty in dRmag2magstat.error;phot.magdouble