J/ApJ/831/102ivo://CDS.VizieR/J/ApJ/831/102doi:10.26093/cds/vizier.18310102CDSKapanadze B.Dorner D.Vercellone S.Romano P.Aller H.Aller M.,Hughes P.Reynolds M.Kapanadze S.Tabagari L.2017-07-03T14:00:59Z2017-03-01T07:47:23ZCDS support team

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

cds-question@unistra.frbl-lacertae-objectsx-ray-sourcesultraviolet-astronomyWe present the results of the Swift and NuSTAR observations of the nearby BL Lac object Mrk 421 during 2013 January-June. The source exhibited a strong long-term variability in the 0.3-10keV and 3-79keV bands with the maximum-to-minimum daily-binned flux ratios of 22 and 95, respectively, in about 3 months, mainly due to unprecedented strong X-ray outbursts by more than an order of magnitude in both bands within 2 weeks in 2013 April when the 0.3-10keV count rate exceeded the level of 200cts/s for the first time, and Mrk 421 became one of the brightest sources in the X-ray sky. The source was also very active on intra-day timescales, and it showed flux doubling and halving timescales of 1.16-7.20hr and 1.04-3.54hr, respectively. On some occasions, the flux varied by 4%-23% within 300-840s. During this period, the source also exhibited some of the most extreme X-ray spectral variability ever reported for BL Lacs-the location of the synchrotron spectral energy distribution peak shifted from a few eV to ~10keV, and the photon index at 1 keV and curvature parameter varied on timescales from a few weeks down to intervals shorter than 1ks. MAGIC and First G-APD Cherenkov Telescope observations also revealed a very strong very high energy (VHE) flare during April 11-17. The UV and HE {gamma}-ray flares were much weaker compared to their X-ray counterparts, and they generally showed significantly stronger correlation with each other than with the X-ray fluxes.2016ApJ...831..102Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/831/102CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/593/A91 : Mrk 421 multi-wavelength variability, 2007-2009 (Ahnen+, 2016)J/ApJS/222/6 : 4.5yr obs. of Mrk421 with ARGO-YBJ + Fermi (Bartoli+, 2016)J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)J/A+A/578/A22 : Mrk421 in March 2010 (Aleksic+, 2015)J/A+A/576/A126 : The 2009 multiwavelength campaign on Mrk421 (Aleksic+, 2015)J/ApJS/209/14 : The Swift/BAT hard X-ray transient monitor (Krimm+, 2013)J/A+A/559/A75 : 43GHz observation of the blazar Mrk 421 (Blasi+, 2013)J/A+A/545/A117 : Monitoring of Mrk 421 at 15 and 24 GHz (Lico+, 2012)J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)J/ApJ/663/320 : IR-through-UV extinction curve (Fitzpatrick+, 2007)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/831/102https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/831/102http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/831/102https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/831/102https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/831/102http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/831/102GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapX-rayUVdefaultJ/ApJ/831/102/table1Summary of the XRT and UVOT observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifier (1)meta.id;obs.param;obsintStDate of the observation start; UTC (year 2013 added by CDS)stime.epochnullableEndDate of the observation end; UTC (year 2013 added by CDS)stime.epochnullableExp[84/10263] Exposure timestime.duration;obs.exposureintCR[7/163] Swift/XRT count ratect/sphot.count;em.X-rayfloate_CR[0.04/0.8] Uncertainty in CRct/sstat.errorfloatuvw1mag[10.5/11.8]? De-reddened Swift/UVOT uvw1 band magnitudemagphot.mag;em.UVfloatnullablee_uvw1mag[0.03/0.08]? Uncertainty in uvw1magmagstat.error;phot.magfloatnullableFuvw1[16.9/52]? De-reddened Swift/UVOT uvw1 band flux densitymJyphot.flux;em.UVfloatnullablee_Fuvw1[0.5/3]? Uncertainty in Fuvw1mJystat.errorfloatnullableuvm2mag[10.5/12]? De-reddened Swift/UVOT uvm2 band magnitudemagphot.mag;em.UVfloatnullablee_uvm2mag[0.03/0.08]? Uncertainty in uvm2magmagstat.error;phot.magfloatnullableFuvm2[15.3/47]? De-reddened Swift/UVOT uvm2 band flux densitymJyphot.flux;em.UVfloatnullablee_Fuvm2[0.2/2]? Uncertainty in Fuvm2mJystat.errorfloatnullableuvw2mag[10.5/12]? De-reddened Swift/UVOT uvw2 band magnitudemagphot.mag;em.UVfloatnullablee_uvw2mag[0.03/0.08]? Uncertainty in uvw2magmagstat.error;phot.magfloatnullableFuvw2[15/46.5]? De-reddened Swift/UVOT uvw2 band flux densitymJyphot.flux;em.UVfloatnullablee_Fuvw2[0.4/3]? Uncertainty in Fuvw2mJystat.errorfloatnullableJ/ApJ/831/102/table2Summary of the NuSTAR observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifiermeta.id;obs.param;obsStDate of the observation start; UTC (year 2013 added by CDS)stime.epochnullableEndDate of the observation end; UTC (year 2013 added by CDS)stime.epochnullableExpExposure timestime.duration;obs.exposureintCRNuSTAR count ratect/sphot.count;em.X-rayfloate_CRUncertainty in CRct/sstat.errorfloatJ/ApJ/831/102/table3Summary of intra-day X-ray variabilities (IDVs) from the XRT and NuSTAR observationsBin[30/120] Bin widthstime.intervalintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFacFacility identifier (NuSTAR or XRT)meta.id;instrcharobsIDObservation identifiermeta.id;obs.param;obscharDur[0.4/23.5] Observed durationhtime.durationfloatchi2[1/460] Reduced {Chi}^2^ of fitstat.fit.chi2floatDOF[4/392] Degrees of Freedom in fitstat.fit.dofintFvar[1/47.5] Fraction rms variability amplitude%stat.stdev;src.var.amplitude;arith.ratiofloate_Fvar[0.06/5.2] Uncertainty in Fvar%stat.errorfloatDela1[1.6/3.2]? Range of photon index at 1keV; first orbitspect.indexfloatnullablee_Dela1[0.01/0.2]? Uncertainty in Dela1stat.errorfloatnullableDela2[0.2/3.1]? Range of photon index at 1keV; second orbitspect.indexfloatnullablee_Dela2[0.01/0.05]? Uncertainty in Dela2stat.errorfloatnullableDelb1[-0.3/0.5]? Curvature parameter; first orbitstat.fit.paramfloatnullablee_Delb1[0.01/0.2]? Uncertainty in Delb1stat.errorfloatnullableDelb2[0.1/0.6]? Curvature parameter; second orbitstat.fit.paramfloatnullablee_Delb2[0.02/0.2]? Uncertainty in Delb2stat.errorfloatnullableDelEp1[0.001/10]? Position of synchrotron SED; first orbitkeVstat.fit.paramfloatnullablee_DelEp1[0.002/2.2]? Uncertainty in DelEp1keVstat.errorfloatnullableDelEp2[0.04/10]? Position of synchrotron SED; second orbitkeVstat.fit.paramfloatnullablee_DelEp2[0.01/2.4]? Uncertainty in DelEp2keVstat.errorfloatnullableJ/ApJ/831/102/table5Summary of sub-hour X-ray variabilityBin[30/120] Bin widthstime.intervalinte_Delb1[0.01/0.2]? Uncertainty in Delb1stat.errorfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFacFacility identifier (NuSTAR or XRT)meta.id;instrcharobsIDObservation identifiermeta.id;obs.param;obscharDur[0.4/23.5] Observed durationhtime.durationfloatchi2[1/460] Reduced {Chi}^2^ of fitstat.fit.chi2floatDOF[4/392] Degrees of Freedom in fitstat.fit.dofintFvar[1/47.5] Fraction rms variability amplitude%stat.stdev;src.var.amplitude;arith.ratiofloate_Fvar[0.06/5.2] Uncertainty in Fvar%stat.errorfloatDela1[1.6/3.2]? Range of photon index at 1keV; first orbitspect.indexfloatnullablee_Dela1[0.01/0.2]? Uncertainty in Dela1stat.errorfloatnullableDela2[0.2/3.1]? Range of photon index at 1keV; second orbitspect.indexfloatnullablee_Dela2[0.01/0.05]? Uncertainty in Dela2stat.errorfloatnullableDelb1[-0.3/0.5]? Curvature parameter; first orbitstat.fit.paramfloatnullableDelb2[0.1/0.6]? Curvature parameter; second orbitstat.fit.paramfloatnullablee_Delb2[0.02/0.2]? Uncertainty in Delb2stat.errorfloatnullableDelEp1[0.001/10]? Position of synchrotron SED; first orbitkeVstat.fit.paramfloatnullablee_DelEp1[0.002/2.2]? Uncertainty in DelEp1keVstat.errorfloatnullableDelEp2[0.04/10]? Position of synchrotron SED; second orbitkeVstat.fit.paramfloatnullablee_DelEp2[0.01/2.4]? Uncertainty in DelEp2keVstat.errorfloatnullableJ/ApJ/831/102/table6Summary of the XRT spectral analysis with the log-parabolic (LP) modelrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifiermeta.id;obs.param;obschara[1/2.9] Photon index at 1kevmeta.code;spect.index;em.X-ray.softfloate_a[0.01/0.05] Uncertainty in astat.errorfloatb[0.09/0.5] Curvature parameterstat.fit.paramfloate_b[0.02/0.2] Uncertainty in bstat.errorfloatEp[0.003/10] Position of synchrotron SEDkeVstat.fit.paramfloate_Ep[0.001/2.2] Uncertainty in EpkeVstat.errorfloatK[0.01/1.1] Normalizationstat.fit.paramfloate_K[0.0009/0.02] Uncertainty in Kstat.errorfloatchi2[0.8/1.4] Reduced {Chi}^2^ of fitstat.fit.chi2floatDOF[69/475] Degrees of Freedom of fitstat.fit.dofintf_DOF[?] Uncertainty flag in DOFmeta.codecharlogFS[-10/-8.5] Log unabsorbed soft (0.3-2keV) flux (in units of erg/s/cm^2^)log(mW.m**-2)phot.fluxfloate_logFS[0.002/0.05] Uncertainty in logFSlog(mW.m**-2)stat.errorfloatlogFH[-10.6/9] Log unabsorbed hard (2-10keV) flux (in units of erg/s/cm^2^)log(mW.m**-2)phot.fluxfloate_logFH[0.005/0.2] Uncertainty in logFHlog(mW.m**-2)stat.errorfloatlogFT[-9.9/-8.2] Log unabsorbed total (0.3-10keV) flux (in units of erg/s/cm^2^)log(mW.m**-2)phot.fluxfloate_logFT[0.002/0.09] Uncertainty in logFTlog(mW.m**-2)stat.errorfloatHR[0.1/1.3] Hardness ratio (1)phot.flux;arith.ratiofloate_HR[0.005/0.04] Uncertainty in HRstat.errorfloatJ/ApJ/831/102/table9Summary of the XRT spectral analysis with a simple power-law (PL) modelHRHardness ratio (2)phot.flux;arith.ratiofloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifiermeta.id;obs.param;obscharGammaPhoton indexmeta.code;spect.indexfloate_GammaUncertainty in Gammastat.errorfloatKNormalizationstat.fit.paramfloate_KUncertainty in Kstat.errorfloatchi2Reduced {Chi}^2^ of fitstat.fit.chi2floatDOFDegrees of Freedom of fitstat.fit.dofintlogFSLog unabsorbed soft (0.3-2 keV) flux (1)log(mW.m**-2)phot.flux;em.X-rayfloate_logFSUncertainty in logFSlog(mW.m**-2)stat.errorfloatlogFHLog unabsorbed hard (2-10 keV) flux (1)log(mW.m**-2)phot.flux;em.X-rayfloate_logFHUncertainty in logFHlog(mW.m**-2)stat.errorfloatlogFTLog unabsorbed total (0.3-10 keV) flux (1)log(mW.m**-2)phot.flux;em.X-rayfloate_logFTUncertainty in logFTlog(mW.m**-2)stat.errorfloate_HRUncertainty in HRstat.errorfloatJ/ApJ/831/102/table10Summary of the NuSTAR spectral analysis with the LP modelrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifiermeta.id;obs.param;obschara[2.2/3.2] Photon index at 1kevmeta.code;spect.index;em.X-ray.softfloate_a[0.006/0.06] Uncertainty in astat.errorfloatb[0.1/0.6] Curvature parameterstat.fit.paramfloate_b[0/0.2] Uncertainty in bstat.errorfloatEp[0.001/4.4] Position of synchrotron SEDkeVstat.fit.paramfloate_Ep[0.002/0.9]? Uncertainty in EpkeVstat.errorfloatnullableK[0.03/11] Normalizationstat.fit.paramfloate_K[0.01/0.4] Uncertainty in Kstat.errorfloatchi2[0.8/11] Reduced {Chi}^2^ of fitstat.fit.chi2floatDOF[158/952] Degrees of Freedom of fitstat.fit.dofintlogFS[-10.2/10.1] Log unabsorbed soft (3-10keV) flux (in units of erg/s/cm^2^)log(mW.m**-2)phot.fluxfloate_logFS[0.001/0.04] Uncertainty in logFSlog(mW.m**-2)stat.errorfloatlogFH[-10.8/-8.6] Log unabsorbed hard (10-79keV) flux (in units of erg/s/cm^2^)log(mW.m**-2)phot.fluxfloate_logFH[0.004/0.04] Uncertainty in logFHlog(mW.m**-2)stat.errorfloatlogFT[-10.1/-8.3] Log unabsorbed total (3-79keV) flux (in units of erg/s/cm^2^)log(mW.m**-2)phot.fluxfloate_logFT[0.002/0.02] Uncertainty in logFTlog(mW.m**-2)stat.errorfloatHR[0.2/1.1] Hardness ratio (1)phot.flux;arith.ratiofloate_HR[0.006/0.06] Uncertainty in HRstat.errorfloatJ/ApJ/831/102/table11Summary of the NuSTAR spectral analysis with a simple PL modelrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintobsIDObservation identifiermeta.id;obs.param;obscharGammaPhoton indexmeta.code;spect.indexfloate_GammaUncertainty in Gammastat.errorfloatKNormalizationstat.fit.paramfloate_KUncertainty in Kstat.errorfloatchi2Reduced {Chi}^2^ of fitstat.fit.chi2floatDOFDegrees of Freedom of fitstat.fit.dofintlogFSLog unabsorbed soft (3-10 keV) flux (1)log(mW.m**-2)phot.flux;em.X-rayfloate_logFSUncertainty in logFSlog(mW.m**-2)stat.errorfloatlogFHLog unabsorbed hard (10-79) keV flux (1)log(mW.m**-2)phot.flux;em.X-rayfloate_logFHUncertainty in logFHlog(mW.m**-2)stat.errorfloatlogFTLog unabsorbed total (3-79 keV) flux (1)log(mW.m**-2)phot.flux;em.X-rayfloate_logFTUncertainty in logFTlog(mW.m**-2)stat.errorfloatHRHardness ratio (2)phot.flux;arith.ratiofloate_HRUncertainty in HRstat.errorfloat