J/ApJ/956/21ivo://CDS.VizieR/J/ApJ/956/21doi:10.26093/cds/vizier/ba-xw-nCDSBellm E.C.Wang Y.van Roestel J.Phillipson R.A.Coughlin M.W.,Tomsick J.A.Groom S.L.Healy B.Purdum J.Rusholme B.Sollerman J.,Bealo P.Lora S.Muyllaert E.Peretto I.Schwendeman E.J.2026-03-02T20:03:02Z2026-01-30T10:35:33ZCDS support team

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

cds-question@unistra.frx-ray-binary-starsultraviolet-photometryvisible-astronomytransient-sourcesUsing the Zwicky Transient Facility, in 2021 February we identified the first known outburst of the black hole X-ray transient XTE_J1859+226 since its discovery in 1999. The outburst was visible at X-ray, UV, and optical wavelengths for less than 20 days, substantially shorter than its full outburst of 320 days in 1999, and the observed peak luminosity was 2 orders of magnitude lower. Its peak bolometric luminosity was only 2x10^35^erg/s, implying an Eddington fraction of about 3x10^-4^. The source remained in the hard spectral state throughout the outburst. From optical spectroscopy measurements we estimate an outer disk radius of 10^11^cm. The low observed X-ray luminosity is not sufficient to irradiate the entire disk, but we observe a surprising exponential decline in the X-ray light curve. These observations highlight the potential of optical and infrared synoptic surveys to discover low-luminosity activity from X-ray transients.2023ApJ...956...21Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/956/21CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-)J/A+A/469/807 : Catalogue of Galactic low-mass X-ray binaries (Liu+, 2007)J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)J/ApJ/699/453 : Determination of black hole masses (Shaposhnikov+, 2009)J/MNRAS/426/1701 : High-frequency QPO in black hole binaries (Belloni+, 2012)J/ApJS/209/14 : The Swift/BAT hard X-ray transient monitor (Krimm+, 2013)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/BaltA/24/395 : X-ray and radio sources in binaries (Malkov+, 2015)J/ApJ/800/17 : Mass-transfer sequences in 16 Galactic LMXBs (Fragos+, 2015)J/other/NewA/47.81 : Distances of X-ray binaries (Islam+, 2016)J/A+A/593/A68 : PTF12os & iPTF13bvn spectra & light curves (Fremling+, 2016)J/ApJS/222/15 : WATCHDOG: all-sky database of Gal. BHXBs (Tetarenko+, 2016)J/A+A/587/A61 : BlackCAT, BH mass in X-ray transient (Corral-Santana+, 2016)J/A+A/645/A18 : SVOM-ECLAIRs known X-ray sources catalogue (Dagoneau+, 2021)J/MNRAS/501/2790 : Swift Bulge Survey. first X-ray results (Bahramian+, 2021)J/ApJ/920/120 : g/r-band observation of AT 2019wey (Yao+, 2021)J/ApJ/930/20 : Neutron star XRB Centaurus X-4 monitoring (Baglio+, 2022)J/A+A/675/A199 : XRBcats. Galactic LMXB Catalogue (Avakyan+, 2023)J/A+A/684/A124 : Galactic LMXBs catalog (Fortin+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/956/21https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/956/21http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/956/21https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/956/21https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/956/21http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/956/21GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapX-rayUVOpticaldefaultJ/ApJ/956/21/fig1aUV/Optical outburst lightcurve for XTE J1859+226recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[59249.5/59274.6] Time; TDB Modified Julian Datedtime.epochdoublemag[18.36/21.32]? Apparent AB magnitude in Filtmagphot.magfloatnullablee_mag[0.03/1.1]? Uncertainty in magmagstat.error;phot.magfloatnullablemagLim[18.1/21.4]? The 5-sigma limiting AB magnitude in Filtmagphot.magfloatnullableFiltBandpass filter namemeta.id;instr.bandpass;instr.filtercharSurveySource of data (1)meta.id;instr.telcharJ/ApJ/956/21/fig1bX-ray outburst lightcurve for XTE J1859+226recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJD[59252/59273.3] Time; Modified Julian Datedtime.epochdoubleRate[0.006/0.21]? The 0.3-10keV count ratect/sarith.rate;phot.count;em.X-raydoublenullableE_Rate[0.003/0.02]? Upper 1-sigma uncertainty in ratect/sstat.error;stat.max;phot.countdoublenullablee_Rate[0.002/0.02]? Lower 1-sigma uncertainty in ratect/sstat.error;stat.min;phot.countdoublenullableRateLim[0.013/0.052]? Upper 5-sigma count ratect/sphot.count;em.X-ray;stat.maxdoublenullable