J/A+A/706/A168ivo://CDS.VizieR/J/A+A/706/A168CDSWebbe R.Quintin E.Webb N.Ponti G.Bao T.Maitra C.Mandel S.,Mondal S.2026-03-02T06:25:50Z2026-02-11T07:28:19ZCDS support team

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

cds-question@unistra.frx-ray-sourcestransient-sourcesastrometryspectroscopyphotometryastronomical-object-identificationvisible-astronomyinfrared-astronomyThe study of astronomical transients at high energies provides insights into some of the most extreme physical events in the universe; however, carrying out their detection and fast follow-up studies are limited by instrumental constraints. Search for Transient Object in New observations using Known Sources (STONKS) is a near-real-time transient detection system for XMM-Newton offering the capability to detect transients in XMM-Newton observations at fainter fluxes than can be achieved with wide survey instruments. We present the transients detected with the STONKS pipeline found in an XMM-Newton multi- year heritage survey of the Galactic plane to identify and classify highly variable X-ray sources that have recently been reported in this region. We examined the alerts created by the STONKS pipeline from over 200 XMM observations of the Galactic plane, screening for instrumental effects. The 78 alerts associated with 70 real astrophysical sources were then subjected to further temporal and spectral analysis. From the 70 sources we identified, we were able to classify 32 with a high degree of confidence, including 7 X-ray binaries, 1 gamma-Cas analogue, and 1 magnetar candidate. Of the 70 sources, 23 were detected for the first time in X-rays. This systematic analysis of publicly available data has shown the value and potential of STONKS in the application to XMM-Newton observations. It will enable the community to detect transient and highly variable sources at fainter fluxes than with any other X-ray transient detection systems.2026A&A...706A.168Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/706/A168CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)II/328 : AllWISE Data Release (Cutri+ 2013)IX/69 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR13 (Webb+, 2023)IX/68 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR12 (Webb+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/706/A168https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/706/A168http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/706/A168https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/706/A168https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/706/A168http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/706/A168GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/706/A168/tablec1 (X-ray properties of STONKS alert sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/706/A168/tablec1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/706/A168/tablec1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/706/A168/tablec1?GETtext/xml+votable180.050000true264.61625-29.47819440.0055555555555555565/7228 6/28808-28809 28813 28815 28818 28824 28826 28828-28829 28831 28848 28873-28875 28896 28900 28902 29266 42450-42451 42455-42457 42460-42462 424811.5062136169708525e-19 1.7003137259100215e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/706/A168?format=asciiX-rayOpticalInfrareddefaultJ/A+A/706/A168/tablec1X-ray properties of STONKS alert sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAlertAlert sources number (Alert)meta.id;meta.mainintXMMXMM observation identifier (OBSID)meta.id.assoclongSourceSource number within the observation (Source)meta.idintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainePosError in right ascension and declination (Error)arcsecstat.errorfloat4XMMIdentifier in the 4XMM DR14 catalogue (4XMM)meta.id.assoccharClassSTONKS alert classification (Alert_Class)src.classcharSpectralSTONKS spectral alert flag (Spectral)meta.codecharFluxObserved X-ray flux (Flux)1e-13mW.m**-2phot.flux;em.X-rayfloatVarTrue variability flag (True_Alert)meta.codecharJ/A+A/706/A168/tablec2Multi-wavelength properties of counterpartsSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAlertAlert sources number (Alert)meta.id;meta.mainintGaiaDR3? Gaia DR3 source identified counterpart (Gaia)meta.id.assocnullableGmag? G-band mean magnitude (m_G)magphot.mag;em.optfloatnullableSepGaia? Angular separation to Gaia counterpart (Sep_Opt)arcsecmeta.id.assoc;pos.angDistancefloatnullableJmag? Observed 2MASS J magnitude (m_J)magphot.mag;em.IR.Jfloatnullablel_JmagLower limit flagmeta.code.errorcharSepNIR? Separation to 2MASS counterpart (Sep_NIR)arcsecpos.angDistancefloatnullableAllWISEAllWISE identified counterpart (AllWISE)meta.id.assoccharW1mag? Observed AllWISE W1 magnitude (m_W1)magphot.mag;em.IR.3-4umfloatnullableSepMIR? Separation to AllWISE counterpart (Sep_MIR)arcsecpos.angDistancefloatnullableSIMBADSIMBAD identified counterpart (SIMBAD)meta.id.assocchar2MASS? 2MASS identified counterpart (2MASS)meta.id.assoccharJ/A+A/706/A168/tablec3Classifications of STONKS alert sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAlertAlert sources number (Number)meta.id;meta.mainintClassSTONKS alert class (Alert_Class)src.classcharMWMulti-wavelength counterparts (MW)meta.codecharD? Distance estimates (d)kpcpos.distancefloatnullablelog(LX)Estimated X-ray luminosity (logL_X)log(1e-07W)phys.luminosity;em.X-rayfloatl_log(FX/FOpt)Lower limit flagmeta.code.errorcharlog(FX/FOpt)X-ray-to-optical flux ratio (logF_X/F_Opt)phot.flux;arith.ratiofloatVarIntra-observation variability flag (Short_Variable)meta.codecharSpectSpectral model (Spectrum)meta.id;stat.fitcharkBT1? Temperature of first component (kT)keVphys.temperaturefloatnullablekBT2? Temperature of second component (kT_2)keVphys.temperaturefloatnullablekBT3? Temperature of third component (kT_3)keVphys.temperaturefloatnullableAbund? Elemental abundance for apec/ray (Abund)phys.abundfloatnullablealpha? Power Law index (alpha)spect.indexfloatnullableObjClassSource classification (Src_Class)src.classcharQSource classification quality flag (Quality)meta.codecharJ/A+A/706/A168/tabled1Results of spectral fitting to STONKS alert sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAlertAlert sources number (Alert)meta.id;meta.mainfloatSpectSpectral Model (Model)meta.id;stat.fitcharNHNeutral H Column Density (N_H)1e+20cm**-2phys.columnDensityfloatE_NH? Upper limit of NH (N_H_upper)1e+20cm**-2stat.error;stat.maxfloatnullablekBT? Temperature of first component (kT)keVphys.temperaturefloatnullableE_kBT? Upper limit of kT (kT_upper)keVstat.error;stat.maxfloatnullablekBT2? Temperature of second component (kT2)keVphys.temperaturefloatnullablee_kBT2? Lower uncertainty of kBT2 (kT2_lower)keVstat.errorfloatnullableE_kBT2? Upper uncertainty of kBT2 (kT2_upper)keVstat.error;stat.maxfloatnullablekBT3? Temperature of third component (kT3)keVphys.temperaturefloatnullablee_kBT3? Lower uncertainty of kBT3 (kT3_lower)keVstat.errorfloatnullableE_kBT3? Upper uncertainty of kBT3 (kT3_upper)keVstat.error;stat.maxfloatnullableAbund? Elemental abundance for apec/ray (Abund)meta.codefloatnullablealpha? Photon index (alpha)spect.indexfloatnullablee_alpha? Lower uncertainty on alpha (alpha_lower)stat.error;pos.eq.rafloatnullableE_alpha? Upper uncertainty on alpha (alpha_upper)stat.error;stat.maxfloatnullabledof? Degrees of Freedom (dof)stat.fit.dofintnullableChi2Model Reduced Chi-squared (Chi2_nu)stat.fit.chi2floate_NH? Lower limit of NH (N_H_lower)1e+20cm**-2stat.errorchare_kBT? Lower limit of kT (kT_lower)keVstat.errorchar