October 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 40544] GRB 251026A: Swift-XRT observations
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42461 SUBJECT: GRB 251026A: Swift-XRT observations DATE: 25/10/26 21:42:15 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source GRB 251026A (SVOM burst-id sb25102605), collecting 1.7 ks of Photon Counting (PC) mode data between T0+5.8 ks and T0+12 ks after the trigger. We have detected 2 sources. These have been automatically classified as follows: * 0 likely counterparts * 0 candidate counterparts * 2 uncatalogued X-ray sources * 0 known X-ray sources We note that neither source is consistent with the SVOM/MXT position given in GCN Circ. 42454. Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J044944.9+514605): ================================== RA (J2000.0): 72.4374 = 04 49 44.98 Dec (J2000.0): +51.7683 = +51 46 05.9 Error: 5.1 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 5.8 arcmin from the SVOM/ECLAIRs position. Mean rate: 0.0123 +/- 0.0033 ct s^-1 Mean flux: (4.6 +/- 1.2)e-13 erg cm^-2 s^-1 Peak rate: 0.0123 +/- 0.0033 ct s^-1 Peak flux: (4.6 +/- 1.2)e-13 erg cm^-2 s^-1 ECF: 3.75e-11 erg cm^-2 ct^-1 assuming NH=1.57e+22 cm^-2, gamma=2.98 determined from a spectral fit. XMM UL: 3.5e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. A SIMBAD object `NVSS J044945+514603' is 7.5" away. There are 2 2MASS objects within the source's 3-sigma error radius. Source 2 (SWIFT J045052.5+515630): ================================== RA (J2000.0): 72.7189 = 04 50 52.54 Dec (J2000.0): +51.9418 = +51 56 30.5 Error: 9.7 (arcsec, radius, 90% confidence). Detect flag: REASONABLE Distance: 9.6 arcmin from the SVOM/ECLAIRs position. Mean rate: (4.0 [+2.6, -1.8])e-3 ct s^-1 Mean flux: (1.74 [+1.10, -0.78])e-13 erg cm^-2 s^-1 Peak rate: (4.0 [+2.6, -1.8])e-3 ct s^-1 Peak flux: (1.74 [+1.10, -0.78])e-13 erg cm^-2 s^-1 XMM UL: 2.3e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. A SIMBAD object `NVSS J045052+515630' is 3.9" away. There are 6 2MASS objects within the source's 3-sigma error radius. All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00045. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42461. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40543] GRB 251025B: OHP/T193 optical detection
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42460 SUBJECT: GRB 251025B: OHP/T193 optical detection DATE: 25/10/26 21:20:15 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> N.A. Rakotondrainibe (LAM), C. Adami (LAM/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), S. basa (UAR Pytheas) report on behalf of the MISTRAL GRB collaboration We carried out observations of the GRB 251025B (Hussein et al., GCN 42437) optical and NIR afterglow (Wu et al., GCN 42438; Gress et al., GCN 42439; Wu et al., GCN 42440; Beardmore et al., GCN 42445; Mohan et al., GCN 42447; Hernández Funget al., GCN 42450; Pereyra et al., GCN 42452; Li et al., GCN 42453; Mo et al., GCN 42459) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 1 exposure of 3 min and 5 exposures of 12 min in the r-band at a midtime of 2025-10-26 20:11:53 UT corresponding to T-T0 = 29.8 hours. The afterglow is well detected in r’ and we measured the following preliminary magnitude: r’ = 20.93+/-0.07 mag (AB) The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We used the STDWeb/STDPipe tools (Karpov 2025). We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Jean Balcaen and the SOPHIE observer Guillaume Hebrard. View this GCN Circular online at https://gcn.nasa.gov/circulars/42460. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40542] GRB 251025B: SVOM/VT optical observations with VHF data
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42440 SUBJECT: GRB 251025B: SVOM/VT optical observations with VHF data DATE: 25/10/25 16:47:24 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu., L.P. Xin, H.L. Li, Y. L. Qiu (NAOC), J. T. Palmerio (CEA), S. Hussein (IJCLab), M. Brunet (IRAP) report on behalf of the SVOM team. SVOM/VT performed an automatic slew on the burst triggered by SVOM/ECLAIRs (Hussein et al., GCN 42437). SVOM/VT began observing the field automatically at 2025-10-25T14:30:18 UTC, 373 seconds after the T0, with the slew of the platform triggered on-board, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. We confirm the clear detection of the source reported by Wu et al.(GCN 42438) and Gress et al.(GCN 42439) in both the VT_B and VT_R bands with the downlinked VHF data. The AB magnitudes were derived as follows: -------------------------------------------- (T-T0)_mid exptime band mag 523 sec 300 sec VT_R 18.61 +/-0.01 523 sec 300 sec VT_B 19.15 +/-0.02 We note that the color of VT_B - VT_R ~ 0.5 mag may indicate a low-to-medium redshift event, following the analysis of Wang et al. (2020, RAA). Additional follow-up observations are encouraged. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42440. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40541] GRB 251025B: J-band detection with WINTER
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42459 SUBJECT: GRB 251025B: J-band detection with WINTER DATE: 25/10/26 17:17:21 GMT FROM: Geoffrey Mo at Caltech / Carnegie Observatories <gmo(a)mit.edu> Geoffrey Mo (Caltech/Carnegie), Benjamin Schneider (LAM), Tomas Ahumada (Caltech), Viraj Karambelkar (Columbia), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of GRB 251025B (Hussein et al., GCN 42437; Beardmore et al., GCN 42445) in the near-infrared J band with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations began at 2025-10-26T04:48:17 UTC in the J band (~14.4 hours after the GRB trigger), consisting of 15 x 120 s exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565) We detect a clear source at the optical counterpart location (Wu et al., GCN 42438; Gress et al., GCN 42439; Wu et al., GCN 42440; Mohan et al., GCN 42447; Hernández Fung et al., GCN 42450; Pereyra et al., GCN 42452; Li et al., GCN 42453), likely during its rebrightening phase, with magnitude J ~ 20.0 mag (AB). WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/42459. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40540] GRB 251026A: SVOM/C-GFT upper limit
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42458 SUBJECT: GRB 251026A: SVOM/C-GFT upper limit DATE: 25/10/26 14:04:34 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng(NAOC), Lei Huang(NAOC), Jianyan Wei (NAOC), J.X Cao (GXU), X. Tian (GXU) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 251026A (sb25102605) detected by SVOM/ECLAIRs (Cao et al., GCN 42454) with LATIOS on SVOM/C-GFT. Observations started at 2025-10-26T10:31:43 UTC, ~2.07 hr after the trig-ger. A series of g, r, and i band images were obtained. No credible candidate was detected within the error box provided by SVOM/MXT (Cao et al., GCN 42454) in our stacked images. The corresponding three sigma upper limit is, mag_i=19.65 at the midpoint of the observations, T₀ + 2.15 hr. The photometry was calibrated against nearby Pan-STARRS1 stars and no correction for Galactic dust extinction was applied. This result is consistent with Postigo et al. (GCN 42456). We thank the observation assistants Bowen Li and Hongxu Xuan 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/42458. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40539] IceCube-251025A: DDOTI Optical Upper Limit
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42457 SUBJECT: IceCube-251025A: DDOTI Optical Upper Limit DATE: 25/10/26 13:42:49 GMT FROM: Rosa Leticia Becerra Godínez at Instituto de Astronomía, UNAM <rbecerra(a)astro.unam.mx> Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report: We observe the field of the IceCube-251025A (bronze) event (IceCube Collaboration, GCN Circ. 42436) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on the Sierra of San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2025-10-26 UTC. DDOTI observed from 10:41 UTC to 12:41 UTC (T+20.9 h to T+22.9 h after the trigger), with a total exposure time of 24 minutes, covering the entire error region reported by IceCube (IceCube Collaboration, GCN Circ. 42436). These observations were interleaved with other scientific programs. Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogues, we detect no uncatalogued sources within the observed field to a 10-sigma limiting AB magnitude of: w > 20.0. Further observations are planned to assess variability. This value is not corrected for the Galactic extinction. We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/42457. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40538] GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42456 SUBJECT: GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit DATE: 25/10/26 11:16:33 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> Antonio de Ugarte Postigo (LAM), Margarita Pereyra (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM), J.X Cao (GXU), X. Tian (GXU): We imaged the field of the SVOM GRB 251026A (Cao et al., GCN Circ. 42454) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-10-26 08:49:51 to 09:08:59 UTC (from 22.5 to 41.6 minutes after the trigger) and obtained 16x60 seconds of exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ pipeline and analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1/SkyMapper catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source within the MXT source position (Cao et al., GCN Circ. 42454) down to the following 5-sigma limit: r > 23.0 mag z > 21.6 mag Further observations are ongoing. 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/42456. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40537] GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42456 SUBJECT: GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit DATE: 25/10/26 11:16:33 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> Antonio de Ugarte Postigo (LAM), Margarita Pereyra (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM), J.X Cao (GXU), X. Tian (GXU): We imaged the field of the SVOM GRB 251026A (Cao et al., GCN Circ. 42454) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-10-26 08:49:51 to 09:08:59 UTC (from 22.5 to 41.6 minutes after the trigger) and obtained 16x60 seconds of exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ pipeline and analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1/SkyMapper catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source within the MXT source position (Cao et al., GCN Circ. 42454) down to the following 5-sigma limit: r > 23.0 mag z > 21.6 mag Further observations are ongoing. 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/42456. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40536] GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42456 SUBJECT: GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit DATE: 25/10/26 11:16:33 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> Antonio de Ugarte Postigo (LAM), Margarita Pereyra (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM), J.X Cao (GXU), X. Tian (GXU): We imaged the field of the SVOM GRB 251026A (Cao et al., GCN Circ. 42454) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-10-26 08:49:51 to 09:08:59 UTC (from 22.5 to 41.6 minutes after the trigger) and obtained 16x60 seconds of exposure in the r and z filters. The data were reduced and coadded with the COLIBRÍ pipeline and analyzed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1/SkyMapper catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source within the MXT source position (Cao et al., GCN Circ. 42454) down to the following 5-sigma limit: r > 23.0 mag z > 21.6 mag Further observations are ongoing. 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/42456. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40535] GRB 251026B: Fermi GBM Final Localization
by GCN Circulars 26 Oct '25

26 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42455 SUBJECT: GRB 251026B: Fermi GBM Final Localization DATE: 25/10/26 09:48:27 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> The Fermi GBM team reports the detection of a likely SHORT GRB "At 07:18:53.33 UT on 26 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251026B (trigger 783155938/251026305). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 132.32, Dec = -12.21 (J2000 degrees, equivalent to J2000 8h 49m, -12d 12'), with a statistical uncertainty of 8.04 degrees. The angle from the Fermi LAT boresight is 19 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251026305/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251026305/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251026305/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/42455. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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