J/ApJ/947/2ivo://CDS.VizieR/J/ApJ/947/2doi:10.26093/cds/vizier/ba-xk-2CDSPartington E.R.Cackett E.M.Kara E.Kriss G.A.Barth A.J.,De Rosa G.Homayouni Y.Horne K.Landt H.Zoghbi A.Edelson R.,Arav N.Boizelle B.D.Bentz M.C.Brotherton M.S.Byun D.,Dalla Bonta E.Dehghanian M.Du PuFian C.Filippenko A.V.,Gelbord J.Goad M.R.Gonzalez Buitrago D.H.Grier C.J.Hall P.B.,Hu C.Ilic D.Joner M.D.Kaspi S.Kochanek C.S.Korista K.T.,Kovacevic A.B.Kynoch D.McLane J.N.Mehdipour M.Miller J.A.,Panagiotou C.Plesha R.Popovic L. CProga D.Rogantini D.,Storchi-Bergmann T.Sanmartim D.Siebert M.R.Vestergaard M.,Ward M.J.Waters T.Zaidouni F.2026-07-02T11:59:01Z2025-04-16T09:23:53ZCDS support team

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

cds-question@unistra.frseyfert-galaxiesactive-galactic-nucleix-ray-sourcesThe AGN STORM 2 Collaboration targeted the Seyfert 1 galaxy Mrk 817 for a year-long multiwavelength, coordinated reverberation mapping campaign including Hubble Space Telescope, Swift, XMM-Newton, NICER, and ground-based observatories. Early observations with NICER and XMM revealed an X-ray state 10 times fainter than historical observations, consistent with the presence of a new dust-free, ionized obscurer. The following analysis of NICER spectra attributes variability in the observed X-ray flux to changes in both the column density of the obscurer by at least one order of magnitude (NH ranges from 2.85_-0.33_^+0.48^x10^22^cm^-2^ to 25.6_-3.5_^+3.0^x10^22^cm^-2^) and the intrinsic continuum brightness (the unobscured flux ranges from 10^-11.8^ to 10^-10.5^erg/s/cm^-2^). While the X-ray flux generally remains in a faint state, there is one large flare during which Mrk817 returns to its historical mean flux. The obscuring gas is still present at lower column density during the flare, but it also becomes highly ionized, increasing its transparency. Correlation between the column density of the X-ray obscurer and the strength of UV broad absorption lines suggests that the X-ray and UV continua are both affected by the same obscuration, consistent with a clumpy disk wind launched from the inner broad-line region.2023ApJ...947....2Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/947/2CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJ/613/682 : AGN central masses & broad-line regions (Peterson+, 2004)J/ApJ/641/L21 : BH mass and velocity dispersion relation (Greene+, 2006)J/ApJ/660/1072 : Unified model of active galactic nuclei (Wang+, 2007)J/other/ChA+A/32.351 : Accretion rate distributions of AGNs (Bao+, 2008)J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)J/ApJ/697/182 : Dust emission from unobscured AGN (Thompson+, 2009)J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)J/ApJ/739/57 : Ultra hard X-ray AGNs in the Swift/BAT survey (Koss+, 2011)J/MNRAS/414/500 : Spitzer/IRS ATLAS project source (Hernan-Caballero+, 2011)J/ApJS/199/8 : Interstellar column density compilation (Gudennavar+, 2012)J/ApJ/753/L2 : Reverberation mapping of AGNs (Assef+, 2012)J/ApJ/761/184 : IR luminosities for dusty AGNs and QSOs (Weedman+, 2012)J/ApJ/788/159 : 17 Seyfert 1 galaxies light curves (Koshida+, 2014)J/ApJS/216/17 : AKARI 2.5-5um spectra of nearby Type-1 AGNs (Kim+, 2015)J/ApJS/217/26 : Lick AGN monitoring 2011: light curves (Barth+, 2015)J/ApJ/813/82 : z<0.06 broad-line AGN emission-line measures (Reines+, 2015)J/A+A/588/A70 : Hard X-ray view of the soft excess in AGN (Boissay+, 2016)J/ApJ/818/L14 : RM AGNs accretion rates and BH masses (Du+, 2016)J/ApJ/831/134 : BH masses & host gal. dispersion vel. (van den Bosch, 2016)J/ApJ/870/123 : Swift optical & UV flux of four AGNs (Edelson+, 2019)J/ApJ/877/23 : SEAMBHs. X. RM campaign compilation (Lu+, 2019)J/ApJ/886/42 : Reverberation mapping & opt. spectra of AGNs (Du+, 2019)J/A+A/625/A122 : CIELO-RGS, soft X-ray ionized emission lines (Mao+, 2019)J/MNRAS/489/3351 : Spectral energy distributions of AGNs (Brown+, 2019)J/MNRAS/494/5793 : IR photometry and SEDs of hard X-ray AGNs (Kilerci+, 2020)J/ApJ/892/18 : X-ray & MIR luminosities of the GBT galaxies (Kuo+, 2020)J/ApJ/897/111 : Compilation of BH, bulge and stellar masses (Zaw+, 2020)J/ApJ/899/82 : Compilation of BH and host properties (Bohn+, 2020)J/ApJ/901/133 : Supermassive BH masses of RM AGNs (Yu+, 2020)J/ApJ/918/50 : Reverberation mapping for Mrk 817 and NGC 7469 (Lu+, 2021)J/other/Ap/64.277 : Catalog of X-ray active galactic nuclei (Paronyan+, 2021)J/MNRAS/510/4796 : INTEGRAL/IBIS 17yr hard X-ray survey (Krivonos+, 2022)J/ApJ/927/42 : Sy1 AGNs with X-ray sp. from NuSTAR+Swift (Kamraj+, 2022)J/A+A/682/A174 : Classification of Markarian galaxies (Mickaelian+, 2024)J/A+A/687/A250 : STONKS Multi-Mission X-ray Catalog (Quintin+, 2024)J/A+A/691/A203 : Multiwavelength properties of unobscured AGN (Gupta+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/947/2https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/947/2http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/947/2https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/947/2https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/947/2http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/947/2GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapX-raydefaultJ/ApJ/947/2/table2NICER count rate and hardnessrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[9181/9636.8] Heliocentric Julian Date; HJD-24500000dtime.epochfloatCRate[0.75/10] The 0.4-8keV count ratect/sarith.rate;phot.count;em.X-rayfloate_HR[0.01/0.06] Uncertainty in HRstat.errorfloate_CRate[0.02/0.12] Uncertainty in CRatect/sstat.error;phot.count;em.X-rayfloatHR[-0.94/-0.47] Hardness ratio (1)phot.flux;arith.ratio;em.X-rayfloatJ/ApJ/947/2/table3Spectral analysis results: observation date and spectral parameters fit using the methods in Section 3.1recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[9181/9637] Heliocentric Julian Date; HJD-24500000dtime.epochfloatlogFO[-12.04/-10.69] Log obscured 0.4-8keV flux; erg/s/cm^2^mW.m**-2phot.flux;em.X-rayfloatE_logFO[0.008/0.1] Upper 68% confidence interval in logFOmW.m**-2stat.error;stat.max;phot.fluxfloate_logFO[0.008/0.11] Lower 68% confidence interval in logFOmW.m**-2stat.error;stat.min;phot.fluxfloatlogFU[-11.77/-10.5] Log unobscured 0.4-8keV flux; erg/s/cm^2^mW.m**-2phot.flux;em.X-rayfloatE_logFU[0.018/0.4] Upper 68% confidence interval in logFUmW.m**-2stat.error;stat.max;phot.fluxfloate_logFU[0.015/0.3] Lower 68% confidence interval in logFUmW.m**-2stat.error;stat.min;phot.fluxfloatFrac[0.15/0.8] Fractional transmittancestat.fit.paramfloatE_Frac[0.018/1] Upper 68% confidence interval in Fracstat.error;stat.maxfloate_Frac[0.018/0.3] Lower 68% confidence interval in Fracstat.error;stat.minfloatNH[2.8/30] Obscurer Hydrogen column density1e+22cm**-2phys.columnDensityfloatE_NH[0/10] Upper 68% confidence interval in NH1e+22cm**-2stat.error;stat.max;phys.columnDensityfloate_NH[0/21] Lower 68% confidence interval in NH1e+22cm**-2stat.error;stat.min;phys.columnDensityfloatlogxi[-0.5/2.2] Log ionization parameter; L/nR^2^phys.ionizParamfloatE_logxi[0/1.7] Upper 68% confidence interval in logxistat.error;stat.max;phys.ionizParamfloate_logxi[0/1.31] Lower 68% confidence interval in logxistat.error;stat.min;phys.ionizParamfloatcvf[0.7/1] Obscurer covering factorarith.factorfloatE_cvf[0/0.07] Upper 68% confidence interval in cvfstat.error;stat.maxfloate_cvf[0/0.1] Lower 68% confidence interval in cvfstat.error;stat.minfloatchi2[0.6/2] Best fit {chi}^2^_{nu}_ valuestat.fit.chi2floatJ/ApJ/947/2/table4NICER source and background count rate for each estimator during the period of continuous Swift monitoringrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[9189.2/9599.5] Heliocentric Julian Date; HJD-24500000dtime.epochfloat3C50-SR[0.5/10]? The "3C50" estimator 0.4-8keV source rate (1)ct/sarith.rate;em.X-rayfloatnullablee_3C50-SR[0.02/0.2]? Uncertainty in 3C50-SR (1)ct/sstat.error;arith.rate;em.X-rayfloatnullable3C50-BR[0.27/2.8]? The "3C50" estimator 0.4-8keV background rate (1)ct/sarith.rate;instr.background;em.X-rayfloatnullableML-SR[0.2/14.1]? Machine learning estimator 0.4-8keV source rate (1)ct/sarith.rate;em.X-rayfloatnullablee_ML-SR[0.02/0.2]? Uncertainty in ML-SR (1)ct/sstat.error;arith.rate;em.X-rayfloatnullableML-BR[0.3/14.4]? Machine learning estimator 0.4-8keV background rate (1)ct/sarith.rate;instr.background;em.X-rayfloatnullableSW-SR[-1/27.5]? Space weather estimator 0.4-8keV source rate (1)ct/sarith.rate;em.X-rayfloatnullablee_SW-SR[0.02/0.16]? Uncertainty in SW-SR (1)ct/sstat.error;arith.rate;em.X-rayfloatnullableSW-BR[0.27/2.5]? Space weather estimator 0.4-8keV background rate (1)ct/sarith.rate;instr.background;em.X-rayfloatnullable