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[vsnet-grb-info 43691] GRB 260829A: GECAM-B observation of a long burst
by GCN Circulars 30 Aug '26

30 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45470 SUBJECT: GRB 260829A: GECAM-B observation of a long burst DATE: 26/08/30 15:44:43 GMT FROM: xueyuan zao <zaoxueyuan(a)gmail.com> Xue-Yuan Zao, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by GRB 260829A, at 2026-08-29T06:08:10.450 UTC, which is also detected by Fermi/GBM (Fermi GBM team, GCN #45464, GCN #45465 and GCN #45467). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of a single pulse with a duration (T90) of 47.0 +/-4.0 s. The GECAM-B light curve can be found here: https://www.bursthub.cn/gcn/2026/gecambgrb260829A.png The time-averaged spectrum from T0+16.0 to T0+32.0 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.15 +0.18/-0.15 and the cutoff energy, parameterized as Epeak, is 466 +138/-94 keV. The event fluence (10-1000 keV) in this time interval is (2.31 +0.13/-0.16) E-05 erg/cm^2. The localization of GRB 260829A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn/gcn/2026/gecambgrb260829A_amati.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/45470. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43690] GRB 260825A: SVOM/GRM observation of a long burst
by GCN Circulars 30 Aug '26

30 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45469 SUBJECT: GRB 260825A: SVOM/GRM observation of a long burst DATE: 26/08/30 10:14:34 GMT FROM: Jin-Ye Luo <jy_luo2002(a)163.com> SVOM/GRM team: Jin-Ye Luo, Chen-Wei Wang, Yue Wang, Hao-Xuan Guo, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Maria Grazia Bernardin (INAF) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 260825A at 2026-08-25T13:07:19.000 (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45439), AstroSat/CZTI (Harsha K. H. et al., GCN #45466), and GECAM-B (Jin-Ye Luo et. al., GCN #45468). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple pulses with a T90 of 47 +8/-5 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn/gcn/2026/svgrb260825A.png In addition, the position of this burst, as determined by Fermi/GBM (RA = 88.3 deg, Dec = -1.2 deg, Error = 5.7 deg, GCN #45439), is located at about 62 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-9 to T0+38 s is best fitted by a power law function. The power law index is -1.06 +0.6/-0.06. The event fluence (10-1000 keV) in this time interval is (1.26 +0.07/−0.07)E-05 erg/cm^2. 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Jin-Ye Luo (IHEP) (luojy(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/45469. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43689] GRB 260825A: GECAM-B observation
by GCN Circulars 30 Aug '26

30 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45468 SUBJECT: GRB 260825A: GECAM-B observation DATE: 26/08/30 09:38:29 GMT FROM: jy_luo2002(a)163.com Jin-Ye Luo, Chen-Wei Wang, Yue Wang, Hao-Xuan Guo, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by GRB 260825A at 2026-08-25T13:07:19.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45439) and AstroSat/CZTI (Harsha K. H. et al., GCN #45466). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 45 +7/-13 s. The GECAM-B light curve can be found here: https://www.bursthub.cn/gcn/2026/gecambgrb260825A.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/45468. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43688] GRB 260829A: Fermi GBM Detection
by GCN Circulars 29 Aug '26

29 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45467 SUBJECT: GRB 260829A: Fermi GBM Detection DATE: 26/08/29 14:12:23 GMT FROM: Christian Malacaria at INAF-OAR <cmalacaria.astro(a)gmail.com> C. Malacaria (INAF-OAR) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 06:08:09.39 UT on 29 August 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260829A (trigger 809676494/260829256). The Final real-time localization was reported in GCN 45464. The GBM light curve consists of a prompt emission followed by a bright peak with a duration (T90) of about 26.4 s (50-300 keV). The time-averaged spectrum from T0+18 to T0+34 s is best fit by a Band function with Epeak = 260 +/- 10 keV, alpha = -0.66 +/- 0.04, and beta = -2.17 +/- 0.08. The event fluence (10-1000 keV) in this time interval is (1.91 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+22 s in the 10-1000 keV band is 19.1 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/45467. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43687] GRB 260825A: AstroSat CZTI detection
by GCN Circulars 29 Aug '26

29 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45466 SUBJECT: GRB 260825A: AstroSat CZTI detection DATE: 26/08/29 08:02:52 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 (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 duration GRB 260825A which was also detected by Fermi (Fermi GBM team, GCN Circ. 45439). The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-08-25 13:07:14.95 UTC. The measured peak count rate associated with the burst is 161 (+58, -1) counts/s above the background in the combined data of all quadrants, with a total of 7311 (+1106, -1122) counts. The local mean background count rate was 660 (+2, -2) counts/s. We measure a T90 of 206 (+23, -17) s from the cumulative Veto light curve. The duration of T90 is long due to a small flare at 2026-08-25 13:09:11.95 UTC. If this is not related to the burst, the primary has T90 of 63 (+6, -26) s. CZTI data products like interactive and downloadable light curves for this GRB can be found at: https://astrosat.iucaa.in/cift/cift_products/525359231.45/S525359231.45_det… 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/45466. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43686] GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
by GCN Circulars 29 Aug '26

29 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45465 SUBJECT: GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256) DATE: 26/08/29 06:34:56 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 809676494 at 06:08:09 on 29 Aug. 2026 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) = 240.0 deg Decl.(2000.0) = -30.5 deg The 1 sigma statistical error radius is 1.5 deg. We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB260829256/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB260829256/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB260829256/json View this GCN Circular online at https://gcn.nasa.gov/circulars/45465. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43685] GRB 260829A: Fermi GBM Final Real-time Localization
by GCN Circulars 29 Aug '26

29 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45464 SUBJECT: GRB 260829A: Fermi GBM Final Real-time Localization DATE: 26/08/29 06:18:41 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 06:08:09 UT on 29 Aug 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260829A (trigger 809676494.389126 / 260829256). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 242.3, Dec = -34.6 (J2000 degrees, equivalent to J2000 16h 09m, -34d 36'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 47.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260829256/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260829256/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260829256/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45464. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43684] IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 29 Aug '26

29 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45463 SUBJECT: IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube DATE: 26/08/29 06:13:48 GMT FROM: Sam Hori at IceCube/U Wisc-Madison <sahori(a)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-260827A (https://gcn.nasa.gov/circulars/45455) in a time range of 1000 seconds centered on the alert event time (2026-08-27 15:27:16.966 UTC to 2026-08-27 15:43:56.966 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-260827A. 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 1.3e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260827A 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 3e+02 GeV and 1e+05 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2026-08-26 15:35:36.966 UTC to 2026-08-28 15:35:36.966 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 1.5e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260827A 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/45463. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43683] IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 29 Aug '26

29 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45462 SUBJECT: IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube DATE: 26/08/29 06:13:33 GMT FROM: Sam Hori at IceCube/U Wisc-Madison <sahori(a)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-260825A (https://gcn.nasa.gov/circulars/45438) in a time range of 1000 seconds centered on the alert event time (2026-08-25 10:45:13.633 UTC to 2026-08-25 11:01:53.633 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-260825A. 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 1.5e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260825A 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 5e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2026-08-24 10:53:33.633 UTC to 2026-08-26 10:53:33.633 UTC). In this case, we report a p-value of 0.03, 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 1.8e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260825A 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/45462. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43682] IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 29 Aug '26

29 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45461 SUBJECT: IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube DATE: 26/08/29 06:13:01 GMT FROM: Sam Hori at IceCube/U Wisc-Madison <sahori(a)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-260825A (https://gcn.nasa.gov/circulars/45438) in a time range of 1000 seconds centered on the alert event time (2026-08-25 10:45:13.633 UTC to 2026-08-25 11:01:53.633 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-260825A. 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 1.5e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260825A 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 5e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2026-08-24 10:53:33.633 UTC to 2026-08-26 10:53:33.633 UTC). In this case, we report a p-value of 0.03, 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 1.8e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260825A 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/45461. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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