J/ApJ/951/134ivo://CDS.VizieR/J/ApJ/951/134doi:10.26093/cds/vizier.19510134CDSPayne A.V.Auchettl K.Shappee B.J.Kochanek C.S.Boyd P.T.,Holoien T.W.-S.Fausnaugh M.M.Ashall C.Hinkle J.T.Vallely P.J.,Stanek K.Z.Thompson T.A.2025-10-01T20:10:23Z2025-09-26T10:24:39ZCDS support team

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

cds-question@unistra.frtransient-sourcesspectroscopyultraviolet-astronomyphotometryvisible-astronomyx-ray-sourcesASASSN-14ko is a nuclear transient at the center of the AGN ESO253-G003 that undergoes periodic flares. Optical flares were first observed in 2014 by the All-Sky Automated Survey for Supernovae (ASAS-SN) and their peak times are well-modeled with a period of 115.2_-1.2_^+1.3^ days and period derivative of -0.0026+/-0.0006. Here we present ASAS-SN, Chandra, HST/STIS, NICER, Swift, and TESS data for the flares that occurred on 2020 December, 2021 April, 2021 July, and 2021 November. These four flares represent flares 18-21 of the total number of flares observed by ASAS-SN so far since 2014. The HST/STIS UV spectra evolve from blueshifted broad absorption features to redshifted broad emission features over ~10days. The Swift UV/optical light curves peaked as predicted by the timing model, but the peak UV luminosities that varied between flares and the UV flux in Flare 20 were roughly half the brightness of the other peaks. The X-ray luminosities consistently decreased and the spectra became harder during the UV/optical rise, but apparently without changes in absorption. Finally, two high-cadence TESS light curves from Flare 18 and Flare 12 showed that the slopes during the rising and declining phases changed over time, which indicates some stochasticity in the flare's driving mechanism. Although ASASSN-14ko remains observationally consistent with a repeating partial tidal disruption event, these rich multi-wavelength data are in need of a detailed theoretical model.2023ApJ...951..134Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/951/134CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2014)J/ApJ/613/682 : AGN central masses & broad-line region sizes (Peterson+, 2004)J/ApJ/687/1201 : SN and LGRB locations in their host galaxies (Kelly+, 2008)J/ApJ/793/38 : Palomar Transient Factory photometric obs. (Arcavi+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)J/MNRAS/455/2918 : Phot. & line luminosities for ASASSN-14li (Holoien+, 2016)J/MNRAS/463/3813 : ASASSN-15oi UBVI M2W1W2 light curves (Holoien+, 2016)J/ApJ/873/92 : Opt. & UV evolution of the TDE iPTF15af (Blagorodnova+, 2019)J/ApJ/883/111 : UV-Opt LCs of ASASSN-19bt detected by TESS (Holoien+, 2019)J/ApJ/883/94 : Optical and UV follow-up of 1ES 1927+654 (Trakhtenbrot+, 2019)J/ApJ/898/161 : 500days of ASASSN-18pg multiwavelength obs. (Holoien+, 2020)J/ApJ/910/83 : Swift phot. recomputed for 38 transients (Hinkle+, 2021)J/ApJ/910/125 : Follow-up photometry of ASASSN-14ko (Payne+, 2021)J/ApJS/255/7 : X-ray monitoring of 1ES 1927+654 (Ricci+, 2021)J/ApJ/930/12 : Phot. & spectroscopy follow-up of ASASSN-20hx (Hinkle+, 2022)J/ApJ/933/196 : Photometry and spectroscopy of ASASSN-17jz (Holoien+, 2022)J/ApJ/926/142 : UV, optical and X-ray evolution of ASASSN-14ko (Payne+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/951/134https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/951/134http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/951/134https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/951/134https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/951/134http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/951/134GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapX-rayUVOpticaldefaultJ/ApJ/951/134/table1Photometry of ASASSN-14ko used in this analysisrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[58410.42/59563.8] Modified Julian Datedtime.epochdoubleindexedBandObservational band (1)meta.code;instr.filtercharLum[-0.04/11.57]? Luminosity in Band, 10^43^erg/s1e+37Wphys.luminosityfloatnullablee_Lum[0.002/1.42]? Uncertainty in Lum1e+37Wstat.errorfloatnullableHR[-0.68/0.5]? X-ray hardness ratio, HR=(H-S)/(H+S) where H=2-10keV and S=0.3-2keVphot.flux;arith.ratiofloatnullablee_HR[0/0.5]? HR uncertaintystat.errorfloatnullable