- vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 42018] GRB 260303A: SVOM detection of a burst
by GCN Circulars 03 Mar '26

03 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43901 SUBJECT: GRB 260303A: SVOM detection of a burst DATE: 26/03/03 07:17:32 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Ziqi Wang, Defeng Kong(GXU), Donghua Zhao(NAOC), Hatsune Goto(Kanazawa Univ.) report on behalf of the SVOM mission team: At 2026-03-03T06:01:47 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260303A (SVOM burst-id sb26030303). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 5 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 7.95 in the [5-20] keV energy band over a time window of 20.48 seconds starting at 2026-03-03T06:01:27. The localization of the best alert is R.A., Dec. 92.9479, 41.1688 degrees: R.A. (J2000) = 6h11m47.49s Dec. (J2000) = 41d10m07.61s with a 90% confidence level (C.L.) radius of 9.89 arcmin (including systematic error of 2 arcmin added in quadrature). We note that the best position (2 overlapped positions) was distant from other 3 detected positions, maybe due to Crab in FoV. The best detection in other 3 triggers are: R.A., Dec. 93.220, 41.184 degrees with 90% confidence level (C.L.) radius of 10.52'. SVOM slewed to the burst. The SVOM/MXT team is waiting for the full dataset to detect and localise the possible SVOM/MXT counterpart. VT began observing the field after the slew. The analysis of the data will be published in a future circular. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is: Ziqi Wang: ziqi.wang(a)st.gxu.edu.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/43901. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42017] GRB 260228A: EP-FXT follow-up observation
by GCN Circulars 03 Mar '26

03 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43900 SUBJECT: GRB 260228A: EP-FXT follow-up observation DATE: 26/03/03 07:00:27 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.H.Cheng, D.Zhu, K.J.Zhang (SWIFAR, YNU), H.C.Ding, T.Wu (AHNU), C.C.Jin (NAOC) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 260228A (SVOM/sb26022802; Julakanti et al., GCN 43882) starting at 2026-02-28T22:50:15 UTC, approximately 5 minutes after the SVOM trigger, with a total exposure time of 5527 s. Six 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_J155124.0+262035 RA (J2000): 237.8501 Dec (J2000): 26.3431 Flux: 2.1373 x 10^-12 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.6673 x 10^-13 erg/s/cm2 (1 sigma) EPF_J155105.1+261820 RA (J2000): 237.7711 Dec (J2000): 26.3055 Flux: 9.6351 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.891 x 10^-14 erg/s/cm2 (1 sigma) EPF_J155123.9+261238 RA (J2000): 237.8498 Dec (J2000): 26.2105 Flux: 7.077 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.6973 x 10^-14 erg/s/cm2 (1 sigma) EPF_J155130.8+261248 RA (J2000): 237.8781 Dec (J2000): 26.2134 Flux: 1.231 x 10^-13 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 2.1478 x 10^-14 erg/s/cm2 (1 sigma) EPF_J155140.7+261349 RA (J2000): 237.9195 Dec (J2000): 26.2303 Flux: 1.5723 x 10^-13 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 3.1532 x 10^-14 erg/s/cm2 (1 sigma) EPF_J155148.8+262150 RA (J2000): 237.9533 Dec (J2000): 26.3640 Flux: 1.0194 x 10^-13 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 2.9166 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/43900. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42016] EP260302a: Einstein Probe detection of an X-ray transient
by GCN Circulars 03 Mar '26

03 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43899 SUBJECT: EP260302a: Einstein Probe detection of an X-ray transient DATE: 26/03/03 02:50:49 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. J. Zhang (THU), Y. H. Cheng, D. Zhu, K. J. Zhang (YNU), H. W. Pan (NAOC) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260302a. The transient triggered EP-WXT (ID: 01709258736) at 2026-03-02T23:39:22 (UTC). The WXT position of the source is R.A. = 133.015 deg, DEC = -66.007 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 132.9655 deg, DEC = -65.9859 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further information will be updated when the telemetry data is received. 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/43899. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42015] The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
by GCN Circulars 03 Mar '26

03 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43898 SUBJECT: The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart DATE: 26/03/03 02:34:27 GMT FROM: Wenxiong Li at NAOC <liwenxiong1992(a)gmail.com> Wenxiong Li (NAOC), Iair Arcavi (TAU), Ido Keinan (TAU), Runduo Liang (NAOC), David Sand (U of Arizona) We observed the position of the EP/WXT trigger 01709258736 with a Las Cumbres 1m telescope at Cerro Tololo Interamerican Observatory, Chile, 1 hour after the Einstein Probe WXT trigger. We took 2x300s exposures in each visit in the broad optical w band. We find an uncataloged source at RA=132.9739, Dec=-65.9837 within the EP/WXT error circle and measure the following preliminary photometry calibrated to the R band: MJD 61102.042 Mag 19.8 View this GCN Circular online at https://gcn.nasa.gov/circulars/43898. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42014] GRB 251130B: TERI Gamma-ray detection
by GCN Circulars 02 Mar '26

02 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43897 SUBJECT: GRB 251130B: TERI Gamma-ray detection DATE: 26/03/02 15:52:59 GMT FROM: nicholasjkirschner(a)gmail.com Nicholas Kirschner (a), Daniel Shy (b), C.C. Cheung (b), Bernard Phlips (b), Michael Streicher (c), James Mason (c), Douglas M. Groves (c), Feng Zhang (c), and Willy Kaye (c) (a) National Research Council Research Associate resident at the U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (b) U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (c) H3D, Inc., 812 Avis Dr., Ann Arbor, MI 48108, USA The cadmium zinc TElluride Radiation Imager (TERI) gamma-ray telescope [1], operating on the International Space Station, reports the detection of GRB 251130B, which was also detected by Fermi/GBM (GCN 42905, 42907), AstroSat/CZTI (GCN 42925), and Glowbug (GCN 42953). Using 1 Hz binning, and adopting T0 = 2025-11-30T15:33:18, we observe the second of the two peaks seen in the Fermi/GBM lightcurve (GCN 42905) at ~T0+78.5s with a peak excess count rate of 276 counts per second (cps) above the 201 cps baseline rate observed in nearby off-source intervals. The analysis results presented here are preliminary and currently lack a detailed response function. TERI is an Office of Naval Research funded technology demonstrator for large-volume pixelated CdZnTe detectors developed, built, and operated by the U.S. Naval Research Laboratory (NRL) in conjunction with H3D, Inc. The pixelated CdZnTe detectors have an energy range of 40 keV to 3 MeV per pixel. It was launched on 2025 April 21 aboard the Department of Defense Space Test Program STP-H10 to the ISS. On the ISS, it is located on the SOX external payload facility on the Columbus module. Analysis of TERI data at NRL is supported by the Office of Naval Research 6.1. [1] Shy, Daniel, et al. "Development of the cadmium zinc TElluride Radiation Imager." Journal of Astronomical Telescopes, Instruments, and Systems 10.4 (2024): 044009-044009 (arXiv:2408.04559). Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/43897. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42013] GRB 260208A: TERI Gamma-ray detection
by GCN Circulars 02 Mar '26

02 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43896 SUBJECT: GRB 260208A: TERI Gamma-ray detection DATE: 26/03/02 15:52:13 GMT FROM: nicholasjkirschner(a)gmail.com Nicholas Kirschner (a), Daniel Shy (b), C.C. Cheung (b), Bernard Phlips (b), Michael Streicher (c), James Mason (c), Douglas M. Groves (c), Feng Zhang (c), and Willy Kaye (c) (a) National Research Council Research Associate resident at the U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (b) U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (c) H3D, Inc., 812 Avis Dr., Ann Arbor, MI 48108, USA The cadmium zinc TElluride Radiation Imager (TERI) gamma-ray telescope [1], operating on the International Space Station, reports the detection of GRB 260208A, which was also detected by Fermi/GBM (GCN 43635, 43673), Fermi/LAT (GCN 43645), GECAM-B (GCN 43658), NuSTAR (GCN 43674), and Glowbug (GCN 43675). Using 1 Hz binning, we find a burst onset at T0 = 2026-02-08T05:07:28 and three emission peaks with excesses of 192, 165, and 130 counts per second (cps) above the 33.2 cps baseline rate observed in nearby off-source intervals, at ~T0+15.5s, 23.5s, and 35.5s, respectively. We use all counts between 40 keV and 3 MeV. The analysis results presented here are preliminary and currently lack a detailed response function. TERI is an Office of Naval Research funded technology demonstrator for large-volume pixelated CdZnTe detectors developed, built, and operated by the U.S. Naval Research Laboratory (NRL) in conjunction with H3D, Inc. The pixelated CdZnTe detectors have an energy range of 40 keV to 3 MeV per pixel. It was launched on 2025 April 21 aboard the Department of Defense Space Test Program STP-H10 to the ISS. On the ISS, it is located on the SOX external payload facility on the Columbus module. Analysis of TERI data at NRL is supported by the Office of Naval Research 6.1. [1] Shy, Daniel, et al. "Development of the cadmium zinc TElluride Radiation Imager." Journal of Astronomical Telescopes, Instruments, and Systems 10.4 (2024): 044009-044009 (arXiv:2408.04559). Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/43896. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42012] GRB 260302A: Fermi GBM Final Real-time Localization
by GCN Circulars 02 Mar '26

02 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43895 SUBJECT: GRB 260302A: Fermi GBM Final Real-time Localization DATE: 26/03/02 14:30:12 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 14:19:40 UT on 2 Mar 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260302A (trigger 794153985.446798 / 260302597). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 239.3, Dec = -61.8 (J2000 degrees, equivalent to J2000 15h 57m, -61d 47'), with a statistical uncertainty of 2.7 degrees. The angle from the Fermi LAT boresight is 20.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260302597/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260302597/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260302597/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43895. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42011] EP260227a: Mondy optical observations
by GCN Circulars 02 Mar '26

02 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43894 SUBJECT: EP260227a: Mondy optical observations DATE: 26/03/02 13:09:06 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the fast X-ray transient EP260227a (Wang et al., GCN 43869) with the AZT-33IK 1.5m telescope of the Mondy observatory starting on 2026-02-28 (UT) 20:55:14 and taking several 90-seconds frames in the R band. The optical counterpart (Eyles-Ferris et al., GCNs 43867, 43877, 43888; Li et al., GCN 43868; Fu et al., GCN 43873; Mandarakas et al., GCN 43874; Eyles-Ferris and Tanvir, GCN 43875; Malesani et al., GCN 43876; Strausbaugh et al., GCN 43879; Bochenek et al., GCN 43880; Gassert et al., GCN 43881; Gupta et al., GCN 43884; Ma et al., GCN 43887; Zhong et al., GCN 43891) is barely detected in the stacked frame. Preliminary photometry and observational details are the following: Date UT start t-T0 Exp. Filter Obj. S/N UL(3 sigma) (mid,days) (n*s) (3sigma) 2026-02-28 20:55:14 1.05053 40*90 R 21.8 2.5 21.5 The photometry is based on several nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43894. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42010] GRB 260228A: CAHA 2.2m telescope optical upper limit
by GCN Circulars 01 Mar '26

01 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43893 SUBJECT: GRB 260228A: CAHA 2.2m telescope optical upper limit DATE: 26/03/01 22:42:20 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct(a)iaa.es> S. Guziy (IAA-CSIC), Y.-D. Hu (GXU), M.D. Caballero-García, M. Gritsevich, I. Pérez-García, R. Sánchez-Ramírez, S-Y. Wu (IAA-CSIC), G. García-Segura (UNAM), M. Blazek, I. Vico (CAHA) and A.J. Castro-Tirado (IAA-CSIC), on behalf of a larger collaboration, report: Following the detection of GRB 260228A by SVOM/ECLAIRs (Julakanti et al., GCNC 43882), we triggered the 2.2 m CAHA telescope (+ CAFOS) at the Calar Alto Observatory (Almería, Spain). Images were obtained starting on Mar. 1 at 03:34 UT (i.e., ~6.7 hours after the trigger) in the Sloan griz bands covering the entire error region. In the co-added images (60 × 6 s), no optical transient is detected down to limiting magnitudes of 22.1 mag (r') and 21.0 (i'). This non-detection is consistent with the reports from SVOM/VT (Li et al., GCNC 43886) and SVOM/COLIBRÍ (Mandarakas et al. GCNC 43892). We thank the staff at Calar Alto Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/43893. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42009] GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
by GCN Circulars 01 Mar '26

01 Mar '26

TITLE: GCN CIRCULAR NUMBER: 43892 SUBJECT: GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit DATE: 26/03/01 17:32:00 GMT FROM: nikos.mandarakas(a)lam.fr Nikos Mandarakas (LAM), Margarita Pereyra (UNAM), Nathaniel R. Butler (ASU), Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), Yashaswi Julakanti, Rob Eyles-Ferris report: We imaged the field of the SVOM GRB 260228A (Julakanti et al., GCN Circ. 43882) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2026-03-01 07:28 to 11:52 UTC (from 10.55 to 14.96 hours after the trigger) and obtained 120 minutes of exposure in the r filter and 129 minutes of exposure in the z filter. The data were reduced, coadded, calibrated, and analysed with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the Pan-STARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, comparing to Pan-STARRS and Legacy Survey (Dey et al. 2019) images, we do not detect any new source within the ECLAIRs uncertainty region (Julakanti et al., GCN Circ. 43882) down to the following 5-sigma limits: r > 23.3 z > 22.5 This upper limit is consistent with the one reported by Li et al. (GCN Circ. 43886). We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. 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/43892. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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