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

[vsnet-grb-info 43007] GRB 260608B: Fermi GBM Final Localization
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44874 SUBJECT: GRB 260608B: Fermi GBM Final Localization DATE: 26/06/08 17:54:52 GMT FROM: oindabimukherjee(a)gmail.com The Fermi GBM team reports the detection of a likely LONG GRB "At 12:41:28.68 UT on 08 June 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260608B (trigger 802615293/260608529). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 56.98, Dec = 64.15 (J2000 degrees, equivalent to J2000 3h 47m, +64d 9'), with a statistical uncertainty of 3.78 degrees. The angle from the Fermi LAT boresight is 116 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608529/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608529/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608529/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/44874. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43006] GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44873 SUBJECT: GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening DATE: 26/06/08 15:49:40 GMT FROM: Rosa Leticia Becerra Godínez at Instituto de Astronomía, UNAM <rbecerra(a)astro.unam.mx> Massimiliano Lincetto (CPPM), Leonardo García García (UNAM), Rosa L. Becerra (UNAM), Antonio de Ugarte Postigo (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Sarah Antier (IJCLAB), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), 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), 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 Sofia Bisero (CEA Saclay) report: We re-imaged the field of GRB 260604C (Fermi GBM Team, GCN Circ. 44822, Gotz et al., GCN Circ. 44823) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-06-08 06:37 to 09:24 UTC (from 3.43 to 3.54 days after the trigger) and obtained 64, 63, and 127 minutes of exposure in the g, r, and z filters respectively. The data were reduced, coadded and analysed 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. In our first epoch reported by Becerra et al. (GCN Circ. 44827), we measured: g-r = 0.13 +/- 0.07 g-z = 0.48 +/- 0.10 In this epoch, we measured: g-r = 0.47 +/- 0.06 g-z = 0.86 +/- 0.09 Our measurements indicate a significant reddening of the source between the two epochs. Moreover, we also observe the rebrightening first reported by the Mondy team (Pankov et al., GCN Circ. 44862). The rise began approximately 30 hours after the trigger and lasted for about 30 hours. Further observations and analysis are ongoing. 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/44873. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43005] GRB 260604C: SVOM/C-GFT upper limit
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44872 SUBJECT: GRB 260604C: SVOM/C-GFT upper limit DATE: 26/06/08 15:20:05 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), Z. Kang (CHO), L.P. Xin（NAOC), S.J. Yin (GXU), X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC), N. Dagoneau, S. Bisero (CEA Saclay) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 260604C (SVOM burst-id sb26060404) detected by SVOM/ECLAIRs (GCN 44823) with LATIOS on SVOM/C-GFT. Observations started at 2026-06-05T15:54:29 UTC, ~19.54 h after the trigger. We obtained 9X90s exposures in the SDSS g filter. After preliminary analysis，we do not detect the optical counterpart (Lipunov et al., GCN 44827; Konno et al., GCN 44828; Zhu et al., GCN 44832, Becerra et al., GCN 44834; Hellot et al., GCN 44835; Gompertz et al., GCN 44837; Gompertz et al., GCN 44843; Saccardi et al., GCN 44844; Chen et al., GCN 44851; Moskvitin et al., GCN 44852; Sasaki et al., GCN 44857 ; Pankov et al., GCN 44858 ; Pankov et al., GCN 44862 ; Burkhonov et al., GCN 44865 ) in the stacked image. The upper limit is measured as follows: g > 21.1 AB (3-sigma, mid-time 19.68 h after the trigger). The photometry was calibrated against Pan-STARRS1 DR1 catalog and no correction for Galactic dust extinction was applied. We thank the observation assistants Hong-Xu Xue and Bo-Wen Li at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/44872. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43004] GRB 260607B: AstroSat CZTI detection
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44871 SUBJECT: GRB 260607B: AstroSat CZTI detection DATE: 26/06/08 13:00:00 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> Harsha K. H. (IUCAA), S. Salunke (IUCAA), A. Arya (IITB), A. Goyal (IITB), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 260607B which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 44859), Fermi LAT (Airasca et. al. , GCN Circ. 44860). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2026-06-07 13:19:41.91 UTC. The measured peak count rate associated with the burst is 508 (+45, -30) counts/s above the background in the combined data of all quadrants, with a total of 8523 (+313, -323) counts. The local mean background count rate was 280 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 45.8 (+0.2, -0.6) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.The light curve showed multiple peaks of emission with the strongest peak at 2026-06-07 13:19:41.36 UTC. The measured peak count rate associated with the burst is 4613 (+124, -120) counts/s above the background in the combined data of all quadrants, with a total of 79352 (+766, -730) counts. The local mean background count rate was 1278 (+4, -5) counts/s. We measure a T90 of 45.8 (+0.1, -0.1) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI data products like interactive and downloadable light curves for this GRB can be found at: https://astrosat.iucaa.in/cift/cift_products/ET20260607T131928/ET20260607T1… CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/44871. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43003] GRB 260608A: SVOM detection of a burst
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44870 SUBJECT: GRB 260608A: SVOM detection of a burst DATE: 26/06/08 12:08:17 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, L. Bouchet (IRAP), C.-W. Wang (IHEP) D.-F. Kong (GXU) report on behalf of the SVOM mission team: At 2026-06-08T11:35:32 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260608A (SVOM burst-id sb26060803), which is also detected by Fermi/GBM (GCN 44868). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 34 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 24.71 in the [8-120] keV energy band over a time window of 81.92 seconds starting at 2026-06-08T11:35:14. The localization of the best alert is R.A., Dec. 81.3711, -48.3879 degrees: R.A. (J2000) = 5h25m29.07s Dec. (J2000) = -48d23m16.62s with a 90% confidence level (C.L.) radius of 3.70 arcmin (including systematic error of 2 arcmin added in quadrature). TThe SVOM/ECLAIRs light curve showed a multiple peak structure with a T90 duration of about 46.839 (-2.959 +3.411) s. This burst was also detected by SVOM/GRM with a significance of 18.20. The SVOM/GRM light curve showed a multiple peak structure with a T90 duration of about 53.73 (-2.457 +2.459) s. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260608A.png Due to Sun constraint, no X-ray observation could be performed by SVOM/MXT and no optical observation could be performed by SVOM/VT for the time being. 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 Chenwei Wang: cwwang(a)ihep.ac.cn Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/44870. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43002] GRB 260608A: Fermi GBM Final Real-time Localization
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44869 SUBJECT: GRB 260608A: Fermi GBM Final Real-time Localization DATE: 26/06/08 11:47:57 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 11:35:31 UT on 8 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260608A (trigger 802611336.05914 / 260608483). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 78.4, Dec = -45.2 (J2000 degrees, equivalent to J2000 05h 13m, -45d 12'), with a statistical uncertainty of 3.2 degrees. The angle from the Fermi LAT boresight is 29.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608483/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608483/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608483/… View this GCN Circular online at https://gcn.nasa.gov/circulars/44869. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43001] GRB 260608A: Fermi GBM Final Real-time Localization
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44868 SUBJECT: GRB 260608A: Fermi GBM Final Real-time Localization DATE: 26/06/08 11:46:30 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 11:35:31 UT on 8 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260608A (trigger 802611336.05914 / 260608483). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 78.4, Dec = -45.2 (J2000 degrees, equivalent to J2000 05h 13m, -45d 12'), with a statistical uncertainty of 3.2 degrees. The angle from the Fermi LAT boresight is 29.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608483/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608483/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608483/… View this GCN Circular online at https://gcn.nasa.gov/circulars/44868. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43000] EP260605a: EP-FXT follow-up observation
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44867 SUBJECT: EP260605a: EP-FXT follow-up observation DATE: 26/06/08 10:47:23 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> A.Li (BNU), C. Y. Wang (THU), Z.-C. Zou (NJU), X. H. Tang (THU), H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: The fast X-ray transient EP260605a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Li et al., GCN 44847) at 2026-06-05T09:31:00 (UTC). Follow-up observation by the Follow-up X-ray Telescope (FXT) on board EP was performed at 2026-06-06T10:39:36(UTC), ~25 hours after the WXT detection. The exposure time of the observation is around 6 ks. The on-ground analysis of the FXT data found an uncatalogued source within the error circle of WXT at R.A. = 273.298 deg, DEC = -40.3945 deg (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic) . The average FXT 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 1.03 x 10^21 cm^-2, and a photon index of 3.3 (-0.6, +0.5). The derived average unabsorbed 0.5-10 keV flux is 1.1 (-0.4, +0.9) ×10^(-13) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. 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/44867. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 42999] GRB 260607A: TRT optical observations
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44866 SUBJECT: GRB 260607A: TRT optical observations DATE: 26/06/08 10:34:45 GMT FROM: L. B. He at NAOC <helb(a)bao.ac.cn> L.B. He (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), J. An, X. Liu, Z.P. Zhu, S.Q. Jiang, L.B. He, D. Xu (NAOC), S.Y. Fu (HUST) report: We observed the optical counterpart candidate, AT2026ong, (Gompertz et. al., GCN 44864) of GRB 260607A detected by Fermi GBM (Fermi GBM Team, GCN 44855), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Fresno, California, U.S.A (SRO). A series of frames in the R-band were obtained. AT2026ong is clearly detected in our stacked image with a brightness of R = 19.2 +/- 0.2 at a median time of ~20.5 hrs post-trigger, calibrated with Pan-STARRS DR2 stars in the field and not corrected for Galactic extinction. There is no decay between the GOTO and TRT observations. The previously reported potential host galaxy of AT2026ong (Gompertz et. al., GCN 44864) has a redshift of z ~ 0.126 from the [REGALADE](https://vizier.cds.unistra.fr/viz-bin/VizieR-3?-source=J/A%2bA/706/A284/regalade&-out.add=.) catalog (Tranin et al., 2026). View this GCN Circular online at https://gcn.nasa.gov/circulars/44866. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 42998] GRB 260604C: GRANDMA further observations
by GCN Circulars 08 Jun '26

08 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44865 SUBJECT: GRB 260604C: GRANDMA further observations DATE: 26/06/08 09:38:41 GMT FROM: antier(a)ijclab.in2p3.fr O. Burkhonov (UBAI), M. Pillas (IAP), T. Leandro de Almeida (LNA), E. Elhosseiny (NRIAG), N. Kochiashvili (AbAO), L. Chen (TSU), A. Simon (TShNU of Kyiv), S. Antier (IJCLAB), M. Coughlin (UMN), S. Ehgamberdiev (UBAI), Y. Rajabov (UBAI), Y. Tillayev (UBAI), N. Sasaki (UEA,LNA), R. Inasaridze (AbAO), V. Zhuzhunadze (AbAO), A. Takey (NRIAG), W. Corradi (LNA), I. Abdusamatjan (TNOT) on behalf of GRANDMA: We conducted further follow-up observations of GRB 260604C (Fermi Team, GCN Circ. 44822, Gotz et al., GCN Circ. 44823) with GRANDMA up to now. We observed a possible re-brightening in r, i, and R thanks to further observations from Two-meter Twin Telescope (TTT) sited at the Teide Observatory, UBAI-AZT-22 at Madainak Observatory, AbAO-T1.5m at Abastumani Observatory, KAO-1.88m at Kottamia Astronomical Observatory, and OPD-1.6m at Observatório do Pico dos Dias (Sasaki et al GCN 44857). This is shown in the public site group of the public ACME service Skyportal/ICARE https://skyportal-icare.ijclab.in2p3.fr/source/GCN-260604_202037. To access, one simply needs to create an account using your ORCID id. Our measurements are aligned with Mondy's report (Pankov GCN 44862). The observations are performed under the P7 campaign of GRANDMA to monitor SVOM alerts and LSST alerts from explosive fast transients filtered by BOOM/Babamul and FINK. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (kilonovacatcher.in2p3.fr). Astrophysics Center for Multimessenger studies in Europe is supported Skyportal/ICARE (contact camille.douzet(a)ijclab.in2p3.fr, skyportal.io). The TTT Observing Time Rights (DTO) used were provided by Light Bridges, SL. View this GCN Circular online at https://gcn.nasa.gov/circulars/44865. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0