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

[vsnet-grb-info 40584] GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42499 SUBJECT: GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143) DATE: 25/10/28 04:28:32 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 783314796 at 03:26:31 on 28 Oct. 2025 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 145.7 deg Decl.(2000.0) = 16.8 deg The 1 sigma statistical error radius is 2.1 deg. We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB251028143/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251028143/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251028143/json View this GCN Circular online at https://gcn.nasa.gov/circulars/42499. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40583] GRB 251028A: MAXI/GSC detection
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42498 SUBJECT: GRB 251028A: MAXI/GSC detection DATE: 25/10/28 04:17:17 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> H. Sugai (Chuo U.), Y. Kawakubo, M. Serino (AGU), H. Negoro, M. Nakajima, K. Takagi, H. Takahashi, H. Nishio (Nihon U.), T. Mihara, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Hiramatsu, Y. Kondo, A. Yoshida (AGU), Y. Tsuboi, N. Nagashima, Y. Ishihara (Chuo U.), M. Shidatsu, C. Kang, T. Nakamoto (Ehime U.), I. Takahashi, Y. Yatsu (Science Tokyo), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), Y. Ueda, K. Fujiwara (Kyoto U.), M. Yamauchi, M. Nishio, C. Hiraizumi (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.), T. Kawamuro (Osaka U.), S. Yamada (Tohoku U) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 03:27:06 UT on October 28, 2025. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (149.003 deg, 17.518 deg) = (09 56 00, +17 31 04) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.27 deg and 0.21 deg, respectively. The roll angle of long axis from the north direction is 49.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 267 +- 43 mCrab (4.0-10.0keV, 1 sigma error). Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners: (148.423, 18.362) deg = (09 53 41, +18 21 43) (J2000) (148.075, 17.954) deg = (09 52 17, +17 57 14) (J2000) (149.164, 17.109) deg = (09 56 39, +17 06 32) (J2000) (149.513, 17.514) deg = (09 58 03, +17 30 50) (J2000) There was no significant excess flux in the previous transit at 02:15 UT with an upper limit of 20 mCrab. View this GCN Circular online at https://gcn.nasa.gov/circulars/42498. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40582] GRB 251028A: Fermi GBM Final Real-time Localization
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42497 SUBJECT: GRB 251028A: Fermi GBM Final Real-time Localization DATE: 25/10/28 03:36:52 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 03:26:31 UT on 28 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251028A (trigger 783314796.860488 / 251028143). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 149.5, Dec = 20.2 (J2000 degrees, equivalent to J2000 09h 58m, 20d 11'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 53.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42497. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40581] The EP-WXT trigger 01709247525 is not a real source
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42496 SUBJECT: The EP-WXT trigger 01709247525 is not a real source DATE: 25/10/28 01:44:18 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. H. Wu (GZHU), A. Li (BNU), H. Q. Cheng and H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709247525 at the time of 2025-10-27T03:28:52.59, is not a real source. View this GCN Circular online at https://gcn.nasa.gov/circulars/42496. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40580] SVOM trigger sb25102702/GRB 251027A is not a GRB
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42495 SUBJECT: SVOM trigger sb25102702/GRB 251027A is not a GRB DATE: 25/10/28 00:05:44 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Y. H.Cheng (YNU), Y. F. Liang (PMO), M. Brunet (IRAP), D. Turpin (CEA), report on behalf of the SVOM mission team: At 2025-10-27T09:38:17 SVOM issued an alert with burst-id: sb25102702. The following circular(s) have been published regarding this event: GCN 42471, 42480, 42481, 42486. After reprocessing the data with the full telemetry, this trigger is no longer considered as an astrophysical source but is due to coding noise from the Crab in the field of view. We apologize for any inconvenience this may have caused. The Burst Advocate (BA) on shift for this alert is Yehao Cheng: yhcheng(a)mail.ynu.edu.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42495. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40579] IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42494 SUBJECT: IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/10/27 22:10:59 GMT FROM: Yuhua Yao at IceCube/UW-Madison <yyao255(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-251025A (https://gcn.nasa.gov/circulars/42436) in a time range of 1000 seconds centered on the alert event time (2025-10-25 13:39:33.261 UTC to 2025-10-25 13:56:13.261 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-251025A. We report a p-value of 1.00 in this time window. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, is 1.4e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-251025A in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 1e+05 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-10-24 13:47:53.261 UTC to 2025-10-26 13:47:53.261 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, is 1.6e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-251025A in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/42494. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40578] GRB 251025B: Swift-XRT confirmation of fading
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42493 SUBJECT: GRB 251025B: Swift-XRT confirmation of fading DATE: 25/10/27 20:42:45 GMT FROM: P.A. Evans at U. Leicester <pae9(a)leicester.ac.uk> P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has reobserved the X-ray afterglow of GRB 251025B (Hussein et al., GCN Circ. 42437, Beardmore et al., GCN Circ. 42245), gathering a further 2.6 ks of exposure from T0+131 ks to T0+154 ks. The X-ray source is detected but has faded significantly, from 0.30 +/- 0.02 ct/sec to 0.009 (+0.003, -0.002) ct/sec (0.3-10 keV), further confirming its identity as the afterglow of this GRB. The best-fitting power-law decay index is 0.95 (+0.15, -0.12). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42493. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40577] GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42492 SUBJECT: GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations DATE: 25/10/27 20:37:15 GMT FROM: soroush shakeri at Iranian National Observatory (INO) - Isfahan University of Technology (IUT) <soroush.physic(a)gmail.com> **Authors: INO340 Transient Follow-up Team** (H. G. Khosroshahi (INO), S. Shakeri (IUT/INO), H. Altafi (INO/IUT), S. Karimi Mianrudi (IUT), Parisa Hashemi (IUT), H. Torkzadeh (IUT), Reza Rezaei (SUT) and Yu Wang (ICRANet). We report optical follow-up observations of the long-duration **GRB 251013C**, detected by the Fermi/GBM team (GCN [42221](https://gcn.nasa.gov/circulars/42221?view=index&query=GRB+251013C&st…) at 2025-10-13 17:39:41 UT, and subsequently observed by SVOM and Swift/XRT. We observed the field of GRB 251013C with **3.4 m Telescope of Iranian National Observatory** ([INO340](https://ino.org.ir/en/)) by using SDSS g, r, and i filters on 2025 October 13, 15, and 16 (UT). We detected the source at the following position R.A. (J2000.0): 23 03 16 Dec.(J2000.0): -00 12 21 Our first observation was done at 20:36:20 UT on October 13, corresponding to ~10,578 s after the trigger of the Fermi/GBM, and the observation extended to ~2.17 days post-trigger. Photometric calibration was carried out using nearby reference stars from Pan-STARRS and SDSS catalogs. The afterglow shows a consistent fading trend typical of long GRB afterglows and a slight brightening in the second day, with magnitudes decreasing from i = 16.3 ± 0.018 → 21.61 ± 0.34, r = 16.63 ±0.20 → 21.99 ± 0.25, and g = 16.75 ± 0.017→ 22.44 ± 0.16. The deepest stacked images (exp:500s) from the third night reached g = 22.44 ± 0.16 mag. The optical images [ GRB 251013C - Filter-r - 13 Oct](https://www.dropbox.com/scl/fi/5104th21jqrydd9box07q/grb251013C13oct.j… [GRB 251013C - Filter-r - 15 Oct](https://www.dropbox.com/scl/fi/dx9iwokwdc2k2s2bqjz2z/grb251013C15oct.j… **We thank the INO340 technical and scientific staff**, M. Bidar, A. Javadi, A. Farhang, H. Shalchian, R. Shomali, R. Ravanmehr, H. Jenab, S. M. Mohajer, H. Sadeghi, M. Rostamian, A. Behnam, A. Karimzadeh, T. Shokatpour, R. Mirzaei, H. Alirezaei, S. Masoudieh. View this GCN Circular online at https://gcn.nasa.gov/circulars/42492. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40576] GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42491 SUBJECT: GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf DATE: 25/10/27 20:04:15 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.P. Osborne (U. Leicester), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara (PSU), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/GBM-detected burst GRB 251026B, collecting 2.0 ks of Photon Counting (PC) mode data between T0+116.7 ks and T0+122.7 ks, centred on the tentative GOTO optical counterpart candidate (GCN Circ. 42470). No X-ray sources have been detected consistent with the estimated 3-sigma GOTO error region (0.8 arcsec). The 3-sigma upper limit in the field ranges from ~0.004 to ~0.005 ct s^-1, corresponding to a 0.3-10 keV observed flux of 1.7e-13 to 2.1e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum). 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/ToO_GRBs/00021872. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42491. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40575] GRB 251025C: Glowbug gamma-ray detection
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42490 SUBJECT: GRB 251025C: Glowbug gamma-ray detection DATE: 25/10/27 19:37:00 GMT FROM: richard.s.woolf.civ(a)us.navy.mil R. Woolf, C.C. Cheung, 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, reports the detection of GRB 251025C, which was also detected by Fermi GBM (GCN 42449), CALET (GCN 42467), and AstroSat CZTI (GCN 42469). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-10-25 23:08:38.104 with a duration of 22.5 s and a total significance of about 46.8 sigma. The light curve comprises an initial fast rise/decay component in the T0 to T0+5s window, followed by secondary emission with slow exponential decay extending to T0+22.5s. Note that data from ~T0 to T0+1.5s and ~T0+3s to T0+5.5s 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/42490. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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