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[vsnet-grb-info 42216] GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44095 SUBJECT: GRB 260310A/AT2026fgk: Detection of temporal steepening in Einstein Probe X-ray data DATE: 26/03/23 21:59:34 GMT FROM: Rahul Jayaraman at Cornell University <rj438(a)cornell.edu> Rahul Jayaraman (Cornell), Gaurav Waratkar (Caltech), K-Ryan Hinds (Caltech), Yogesh Wagh (LJMU), Daniel Perley (LJMU), Anna Y. Q. Ho (Cornell), S. Y. Fu (HUST), R. D. Liang, M. J. Liu, Z. X. Ling, Hui Sun, Weimin Yuan (NAO, CAS), Genevieve Schroeder (Cornell), Xander J. Hall (CMU), Michael Coughlin (UMN), Aleksandra Bochenek (LJMU), and Jesper Sollerman (Stockholm) report: The Follow-up X-ray Telescope on board the Einstein Probe has continued to monitor the X-ray afterglow of GRB 260310A (Fermi GBM team, GCN 43951; Arya et al., GCN 43958; Jayaraman et al., GCN 43994), which is associated with the optical transient AT2026fgk (Konno et al., GCN 43974; Hinds et al., AstroNote 2026-65). Observations with duration ~3 ks were taken at intervals of roughly every 2 days after the initial detection of this source in X-rays (Jayaraman et al., GCN 43994). With four further epochs of data since the initial detection, we find evidence for a steepening in the X-ray light curve at around 8 ± 2 days after the burst, with the decay slope steepening from roughly –0.3 to –1.6. The photon index measured by EP remains at roughly 1.5 throughout these observations. This steepening appears contemporaneous with an observed steepening at a similar epoch post-burst in r-band photometric data taken by the SED Machine on the Palomar P60 telescope, which will be reported in a forthcoming Circular. Launched on January 9, 2024, the Einstein Probe is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is supported by the Strategic Priority Program on Space Sciénce of the Chinese Academy of Sciences, in collaboration with the European Space Agency, the Max-Planck-Institute for Extraterrestrial Physics (Germany), and the Centre National d'études Spatiales (France). View this GCN Circular online at https://gcn.nasa.gov/circulars/44095. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42215] GRB 260322A: Fermi GBM Final Localization
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44094 SUBJECT: GRB 260322A: Fermi GBM Final Localization DATE: 26/03/23 17:56:30 GMT FROM: Utkarsh Pathak at IIT Bombay <utkarshpathak.07(a)gmail.com> The Fermi GBM team reports the detection of a likely SHORT GRB "At 10:45:40 UT on 22 March 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260322A (trigger 795869144/260322448). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 301.0, Dec = -61.8 (J2000 degrees, equivalent to J2000 20h 3m, -61d 46'), with a statistical uncertainty of 7.9 degrees. The angle from the Fermi LAT boresight is 59.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260322448/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260322448/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260322448/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/44094. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42214] GRB 260320A: Glowbug gamma-ray detection
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44093 SUBJECT: GRB 260320A: Glowbug gamma-ray detection DATE: 26/03/23 17:34:44 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, confirms the detection of GRB 260320A, which was detected by NuSTAR (GCN 44064), SVOM/GRM (sb26032003), Insight-HXMT/HE (GCN 44077), and Konus-Wind (Trig_Time 19:40:01.257). The burst onset is at 2026-03-20 19:40:02, with a peak at ~T0+1.5s, and a burst duration of ~7s. Note that data throughout the detection interval suffered from deadtime in various detectors. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/44093. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42213] EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44092 SUBJECT: EP260321a / AT2026gzf: VLT/X-shooter detection of supernova-like spectral features at z = 0.0344 DATE: 26/03/23 17:12:25 GMT FROM: nrt3(a)le.ac.uk D. Xu (NAOC), G. Corcoran (UCD), J. An (NAOC), L. Izzo (INAF/OACN), N. Habeeb (Leicester), N. R. Tanvir (Leicester), A. J. Levan (Radboud and Warwick), C. C. Thoene (AbAO), S. Schulze (Weizmann), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI), A. Saccardi (CEA/Irfu), A. Martin-Carrillo (UCD), G. Pugliese (API), A. de Ugarte Postigo (LAM), A. L. Thakur (INAF-IAPS) report on behalf of the Stargate collaboration: We observed the variable point source, AT2026gzf, (Tanvir et al., GCN 44082; see also Lee et al., GCN 44070; Aryan et al., GCN 44081; Ahumada et al., GCN 44084; Liu et al., GCN 44087) associated with X-ray transient EP260321a (Huang et al., GCN 44068) with the X-shooter spectrograph on the ESO VLT UT3 (Melipal) beginning on 2026-02-23 at 00:38 UT (36.1 hr post-trigger). Our observations consisted of 4x600 s exposures, and span the wavelength range 3000-20600 AA. Bright continuum flux is visible in all three arms of the spectrum. In addition to the blue continuum and narrow emission lines reported for the previous MUSE observation (Tanvir et al., GCN 44082), our X-shooter spectrum shows broad features below 5000 AA, similar to those seen in the early spectra of core-collapse supernovae, and inconsistent with those seen in typical young stellar populations. However, we caution that at this early phase there are limited templates for comparison, combined with some contribution from any underlying cluster light, and a search for matches within GELATO and SNID does not, at this time, yield a firm classification. Furthermore, the detection of narrow absorption features due to Ca II at z = 0.0344 conclusively excludes a Milky Way origin for this transient. We acknowledge excellent support of the ESO observing staff at Paranal, in particular Alonso Luna Ruiz Fernandez, Elyar Sedaghati, Lorena Faundez and Marcela Espinoza. View this GCN Circular online at https://gcn.nasa.gov/circulars/44092. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42212] EP260321a: COLIBRÍ further optical observations and brightening
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44091 SUBJECT: EP260321a: COLIBRÍ further optical observations and brightening DATE: 26/03/23 16:06:10 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> Antonio de Ugarte Postigo (LAM), Leonardo García García (UNAM), Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We imaged the field of EP260321a (Huang et al., GCN Circ. 44068, 44075) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope, following our previous observation (Aguilar-Ruiz et al. GCN Circ. 44076). We observed in two epochs between 2026-03-23 04:40 to 10:04 UTC (between 40.17 and 45.57 hours after the trigger) and obtained imaging in the g, r, i, z and y bands. The data were reduced and coadded with the ASU COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. From our first observation, at a mid epoch T+16.33 h after the EP detection, to the second epoch of last night, at a mid epoch of T+43.61 h, the transient reported by Lee et al. (GCN Circ. 44070), has increased in brightness in r-band by 1.3+/-0.1 mag consistently with the reported evolution of the source (Lee et al. GCN Circ. 44070, Aryan et al. GCN Circ. 44081, Tanvir et al. GCN Circ. 44082, Moran et al. GCN Circ. 44083, Ahumada et al. GCN Circ. 44084, Liu et al. GCN Circ. 44087 and Sankar et al. GCN Circ. 44089). Our latest photometric measurement is r = 18.67 +/- 0.02 mag but we caution that the value is likely affected by the contribution of the underlying galaxy. Further observations are planned. We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/44091. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42211] Fermi Gamma-ray Burst Monitor trigger 795918973/260323025 is not a GRB
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44090 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 795918973/260323025 is not a GRB DATE: 26/03/23 15:55:17 GMT FROM: Suman Bala at USRA <sumanbala2210(a)gmail.com> S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 795918973/260323025 at 00:36:08.73 UT on 23 March 2026, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to particle event." View this GCN Circular online at https://gcn.nasa.gov/circulars/44090. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42210] EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44089 SUBJECT: EP260321a: Continued brightening from Kinder follow-up of the emerging supernova candidate DATE: 26/03/23 15:36:09 GMT FROM: Janet Chen at National Central University <janetstars(a)gmail.com> A. Sankar.K, A. Aryan, T.-W. Chen, W.-J. Hou, C.-S. Lin (all NCU), S. Yang (HNAS), A. K. H. Kong (NTHU), S. J. Smartt, J. Gillanders (both Oxford), M. Nicholl (QUB), T. Moriya (NAOJ), M. Saillenfest (LTE, Paris Observatory), Y.-N. Lee (NTNU), M.-H. Lee, A. Dutta, Y.-H. Lee, Y.-C. Pan, C.-C. Ngeow, C.-H. Lai, H.-C. Lin, H.-Y. Hsiao, J.-K. Guo (all NCU), Y. J. Yang (NYUAD), Z. N. Wang, D. C. Qiang, L. L. Fan (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz M. Huber, K. Chambers (all IfA, Hawaii) report: We obtained further optical observations of the field of the fast X-ray transient EP260321a (Huang et al., GCN 44068, 44075) using the 1m LOT at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen et al. 2025, ApJ, 983, 86; Aryan et al. 2025, ApJS, 281, 20). The new LOT observations started at UTC 12:42 on March 23rd 2026 (MJD 61122.5295), corresponding to 48.20 hr after the EP-WXT trigger. At the refined EP/FXT position, coincident with the blue variable source first noted by Lee et al. (GCN 44070) and further discussed by Tanvir et al. (GCN 44082), Ahumada et al. (GCN 44084), and Liu et al. (GCN 44087), we detect the source in the g band. We used the AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform PSF photometry for this object: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | Seeing | Airmass LOT | g | 61122.5295 | 48.20 | 300 * 1 | 18.30 +/- 0.03 | 1".02 | 1.14 The presented magnitude is calibrated using field stars from the ATLAS-RefCat2 catalog from MAST (Tonry et al. 2018, ApJ, 867, 105), is reported in the AB system, and is not corrected for the expected Galactic foreground extinction of A_g = 0.08 mag in the direction of the transient (Schlafly & Finkbeiner 2011). Compared with our previous LOT measurement of g = 18.77 +/- 0.04 mag at 23.99 hr post-trigger (Aryan et al., GCN 44081), the source has brightened by approximately 0.47 mag. This is also consistent with, and extends, the re-brightening trend reported by Liu et al. (GCN 44087), indicating that the source is still rising. Our time resolved monitoring of this source during the six hours after the FXT detection with the LOT (Lee et al., GCN 44070, Aryan et al., GCN 44081) indicates a sharp decline of 0.3 mag within the first 2 hours followed by a continued, monotonic rise, now at g = 18.3 at t-t0 = 48.2 hr. With the spectroscopic observation from Tanvir et al. (GCN 44082) indicating that the source may be associated the z = 0.0343, we propose the LOT optical lightcurve could be explained by the shock cooling and a rise from a supernovae associated with the blue point like source visible in the archive images, also proposed by Liu et al. (GCN 44087). At M_g ~ -17.7, this is now at supernova-like luminosities, which would be consistent with Huang et al. (GCN 44075) interpretaiton of the EP260321a as shock breakout signature. The luminosity of the blue progenitor source would be very large for a single star, lying between M_r = -15 to -16. Elevated, high luminosity has been seen in LBV type precursors (e.g. SN1961V, Kochanek et al. 2011, ApJ 737, 76; and other LBV precursors, Smith et al. 2010, AJ 139, 1451), but this case would be extreme. We note that long term Pan-STARRS monitoring shows this source to be variable over 7 years, with flux variations in the w-band difference imaging around 21 < w < 22. Further spectroscopic observations are required to determine if the transient shows high expansion velocities and lines that definitively place it in the z=0.0343 host. View this GCN Circular online at https://gcn.nasa.gov/circulars/44089. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42209] EP260214b: ATCA 6 GHz detection
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44088 SUBJECT: EP260214b: ATCA 6 GHz detection DATE: 26/03/23 15:25:11 GMT FROM: Aishwarya L Thakur at INAF-IAPS, Rome <aishth(a)outlook.com> G. Gianfagna, G. Bruni, A. L. Thakur, M. Fanelli, L. Piro (INAF-IAPS) report: We re-observed the Fast X-ray Transient EP260214b (J Yang et al., GCN 43744, H Yang et al., GCN 43779) with the Australian Telescope Compact Array (ATCA) radio telescope using the 4-cm receiver. Observations were performed on March 20 2026 (at a mean epoch of ~34 days after the EP trigger and 17 days after our last observation; see Gianfagna et al., GCN 43924) for a total of 5 hours. Data were reduced and imaged with standard CASA procedures. The final 6 GHz image has an RMS of 12 uJy/beam. We detect radio emission at a flux density of ~0.04 mJy at a position consistent with the optical counterpart (He et al.). GCN 43745, Watson et al. GCN 43747, Le Floch et al. GCN 43749, Pérez-Fournon et al. GCN 43750, Russeil et al. 43752,Li et al. GCN 43755, Vijayjumar et al. GCN 43757, Becerra et al. GCN 43758, Yang et al. GCN 43760, Aaryan et al. GCN 43762, Bochenek et al. GCN 43764, Kar et al. GCN 43774, Volnova et al. GCN 43775). Further ATCA observations are planned. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (grid.421683.a), which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. View this GCN Circular online at https://gcn.nasa.gov/circulars/44088. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42208] EP260321a: Early TRT rising followed by JinShan decaying and then re-rising
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44087 SUBJECT: EP260321a: Early TRT rising followed by JinShan decaying and then re-rising DATE: 26/03/23 11:26:51 GMT FROM: liuxing(a)nao.cas.cn X. Liu, D. Xu (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan, K. Noysena (NARIT), J. An, Z.P. Zhu, N.C. Sun, W.X. Li, Z. Fan, S.Q. Jiang, L.B. He (NAOC), S.Y. Fu (HUST), J.Z. Liu (XAO) report on behalf of a large group: Upon the alert of EP260321a detected by Einstein Probe (Huang et al., GCN 44068), we observed the field of EP260321a using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at New South Wales, Australia (SBO), and then using the 100B telescope of the JinShan project, located at Altay, Xinjiang, China. The TRT observation started at 12:52:13 UT on 2026-03-21, i.e., 21.9 mins after the EP-WXT trigger. No uncatalogued optical transient is detected within the EP-FXT error cicle (Huang et al., GCN 44068) down to R ~ 20.5 mag. We noticed the brightening of the catalogued blue point-like source (R.A. 09:59:42.880, Dec. 00:25:06.29, J2000), if compared with PanSTARRS and Legacy Survey, in the outskirt of the galaxy, SDSS J095942.88+002506.2, with a redshift z = 0.0343 in the DESI Legacy Survey DR1 spectroscopic catalogue, mentioned by Kinder (Lee et al., GCN 44070) and then spectroscopically confirmed at VLT/MUSE (Tanvir et al., GCN 44082). The point source has R ~ 19.0 (Vega) at a median time of 27.6 mins post-trigger, calibrated with PanSTARRS in which the source has r = 19.85 +/- 0.03 mag (AB). The JinShan 100B telescope observed the field in g- and r- bands in the nights of 2026-03-21 and 2026-03-22. In the first night, the blue source decayed a bit to g ~ 18.9 (AB and hereafter) at 2.3 hrs post-trigger and r ~ 19.3 mag at 2.8 hrs post-trigger. And the g-band brightening, if subtracted using the PanSTARS templates, is more prominent than in the r-band, suggesting the transient itself is also quite blue. Together with the rather deep ZTF pre-EP upper limit (Ahumada et al., GCN 44084), the TRT observation, and the Kinder first observation (Lee et al., GCN 44070), the transient shows a fast rising around the EP trigger time and then starts to decay around the first Kinder observation. The decaying behavior is consistent with the cooling of Shock Break-Out (SBO) of a SN-like event (Huang et al., GCN 44075) and a thermal-like spectrum at VLT/MUSE (Tanvir et al., GCN 44082). In the second night, the blue source re-brightened to g ~ 18.5 at 28.5 hrs post-trigger and r ~ 18.8 mag at 29.0 hrs post-trigger, which are also brighter than the second Kinder observation that is a bit earlier than the second JinShan (Aryan et al. GCN 44081). This indicates that a SN-like main component is emerging and will likely continue to brighten to a peak in the coming days. View this GCN Circular online at https://gcn.nasa.gov/circulars/44087. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42207] GRB 260321A: EP-FXT follow-up observation
by GCN Circulars 23 Mar '26

23 Mar '26

TITLE: GCN CIRCULAR NUMBER: 44086 SUBJECT: GRB 260321A: EP-FXT follow-up observation DATE: 26/03/23 03:51:16 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Z.-C. Zou, Y. H. Jiang (NJU), J. P. Chen (SYSY), Y. J. Yi (BNU) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 260321A (SVOM/sb26032123; Brunet et al., GCN 44071) starting at 2026-03-22T15:23:32 UTC, approximately 21 hours after the SVOM trigger, with a total exposure time of 4565 s. Four uncataloged sources are detected within the ECLAIRs error circle. Preliminary analysis on these sources is automatically conducted, and the details are listed as follows. EPF_J143847.8+314542 RA (J2000): 219.6990 Dec (J2000): 31.7616 Flux: 9.265 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 3.498 x 10^-14 erg/s/cm2 (1 sigma) EPF_J143759.7+314425 RA (J2000): 219.4989 Dec (J2000): 31.7404 Flux: 2.9252 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.2651 x 10^-14 erg/s/cm2 (1 sigma) EPF_J143833.9+314628 RA (J2000): 219.6440 Dec (J2000): 31.7719 Flux: 5.9349 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 2.0193 x 10^-14 erg/s/cm2 (1 sigma) EPF_J143845.7+313613 RA (J2000): 219.6902 Dec (J2000): 31.6037 Flux: 8.0698 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.9625 x 10^-14 erg/s/cm2 (1 sigma) Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/44086. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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