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

[vsnet-grb-info 39883] LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41817 SUBJECT: LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search DATE: 25/09/12 20:13:49 GMT FROM: Zsuzsa Marka at IceCube/Columbia University <zsuzsa(a)astro.columbia.edu> IceCube Collaboration (http://icecube.wisc.edu/) reports: We have performed a search for track-like muon neutrino candidate events detected by IceCube consistent with the sky localization of the low-significance gravitational-wave candidate event S250912s in a time range of 1000 seconds centered on the alert event time (2025-09-12 18:13:09 UTC to 2025-09-12 18:29:49 UTC) [1,2]. During this time period, IceCube was collecting good quality data. A single hypothesis test was conducted using a Bayesian approach to quantify the joint GW + neutrino event significance, which assumes a binary merger scenario and accounts for known astrophysical priors, such as GW source distance, in the statistical significance estimation [3]. Two track-like events were found in spatial and temporal coincidence with the gravitational-wave candidate S250912s calculated from the map circulated in the S250912s-2-Preliminary notice. This represents an overall p-value of 0.00927 for the Bayesian search. The p-value measures the consistency of the observed track-like events with the known atmospheric backgrounds for this single map (not accounting for statistical trials from multiple GW events). Further details are available at https://gcn.nasa.gov/missions/icecube and at https://roc.icecube.wisc.edu/public/LvkNuTrackSearch. Properties of the coincident event are shown below: dt(s) RA(deg) Dec(deg) Angular uncertainty(deg) p-value(Bayesian) ------------------------------------------------------------------------------------- -276.12 284.52 44.13 16.11 0.0115 19.10 275.72 24.65 1.44 0.0530 where: dt = Time of track event minus time of GW trigger (sec) Angular uncertainty = Angular uncertainty of track event: the radius of a circle representing 90% CL containment by area. p-value = the individual p-value for the specific track event from this search. 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] M. G. Aartsen et al 2020 ApJL 898 L10 [2] Abbasi et al. Astrophys.J. 944 (2023) 1, 80 [3] I. Bartos et al. 2019 Phys. Rev. D 100, 083017 View this GCN Circular online at https://gcn.nasa.gov/circulars/41817. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39882] EP250908c: tentative VLT/FORS2 redshift z = 2.87
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41816 SUBJECT: EP250908c: tentative VLT/FORS2 redshift z = 2.87 DATE: 25/09/12 16:10:17 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> D. B. Malesani (DAWN/NBI and Radboud), L. Izzo (INAF/OACn and DARK/NBI), A. Saccardi (CEA/Irfu), J. An (NAOC), G. Corcoran (UCD), V. D’Elia (ASI/SSDC), M. Garnichey (LUX-Paris Obs.), P. G. Jonker (Radboud), A. J. Levan (Radboud and Warwick), A. Martin-Carrillo (UCD), E. Palazzi (INAF/OAS), G. Pugliese (API), D. Xu (NAOC), report on behalf of a larger collaboration: We observed the optical counterpart (Malesani et al., GCN 41760; Ma et al., GCN 41761; Rau, GCN 41773) of the fast X-ray transient EP250908c (Zhang et al., GCNs 41754, 41763) using the ESO VLT UT1 equipped with the FORS2 spectrograph. In the acquisition image (mid time 2025 Sep 9.134 UT, or 3.37 hr after the EP trigger) we measure a magnitude V = 21.4 +- 0.2 (calibrated using archival zeropoints). A spectrum covering the wavelength range 3800-8600 AA was secured using grism 300V and no order-sorting filter, with a total exposure time of 3x600 s. A faint trace is detected down to ~4790 AA, where a spectral break is observed. If due to Lyman alpha, this would correspond to a redshift of ~2.9. Consistently, a few, weak absorption features are detected, which can be interpreted as C II 1334, Si IV 1393,1402, Si II 1526, C IV 1548,1550, all at a common redshift of z = 2.87. Given the low S/N of the continuum, we caution that this redshift solution should be considered tentative. Rectifying what was stated in our previous report (Malesani et al., GCN 41760), we note the presence of an extended object in the Legacy Survey underlying the afterglow position, which is a candidate host galaxy for EP250908c. With a Legacy Survey magnitude of r = 23.1, this corresponds to M(UV) = -22.4 (AB) at z = 2.87. No emission lines are visible in our spectrum to determine the redshift of this object. We acknowledge excellent support from the observing staff in Paranal, in particular Julien Drevon, Jonathan Smoker and Marcela Espinoza. View this GCN Circular online at https://gcn.nasa.gov/circulars/41816. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39881] EP250911a: Upper limit from Fermi-GBM Observations
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41815 SUBJECT: EP250911a: Upper limit from Fermi-GBM Observations DATE: 25/09/12 14:23:51 GMT FROM: mariaedvige.ravasio(a)ru.nl M. E. Ravasio and P.G. Jonker (Radboud Univ.) on behalf of the Einstein Probe Team and E. Burns (LSU) on behalf of the Fermi-GBM Team, report: Fermi-GBM had full spatial coverage of the transients EP250911a (Liang et al., GCN 41788 and GCN 41809) detected by EP-WXT, and found to be at z=3.84 (Malesani et al., GCN 41811). There was no Fermi-GBM onboard trigger around the refined EP trigger time T0=2025-09-11T08:57:55 (UTC). The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals, was run in the time interval [T0-50; T0+500] s, seeking signals between 64 ms and 32.768 s in duration. No signal consistent with the EP transients, both temporally and spatially, is identified, as confirmed also by visual inspection of the data. Assuming a “normal” spectral template (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3), whose alpha value is consistent with the power law index reported by EP (Liang et al., GCN 41809), and a timescale of 8.192 s, we derive a flux upper limit of 5.3e-08 erg/cm2/s in the energy band 10-1000 keV. [1] Goldstein et al. 2019 arXiv:1903.12597 View this GCN Circular online at https://gcn.nasa.gov/circulars/41815. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39880] LIGO/Virgo/KAGRA S250912f: Updated Sky localization
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41814 SUBJECT: LIGO/Virgo/KAGRA S250912f: Updated Sky localization DATE: 25/09/12 13:28:26 GMT FROM: natalie.williams(a)uni-potsdam.de The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Livingston Observatory (L1) and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S250912f (GCN Circular 41810). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250912f For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 298 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2740 +/- 722 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41814. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39879] GRB 250911A: GECAM-B detection
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41813 SUBJECT: GRB 250911A: GECAM-B detection DATE: 25/09/12 13:00:39 GMT FROM: zhangjinpeng(a)ihep.ac.cn Jin-Peng Zhang, Yang-Zhao Ren, Chen-Wei Wang, Shao-Lin Xiong and Yue Huang (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by GRB 250911A at 2025-09-11T01:29:28.250 UTC (denoted as T0), which was also observed by Swift (Palmer et al., GCN 41781). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of a weak precursor and a bright pulse with multiple spikes, with a duration (T90) of 35.4 +1.1/-1.7 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb250911A.png GECAM-B localized this burst to the following position (J2000): Ra: 262.0 deg Dec: -20.2 deg Err: 4.1 deg (1-sigma, statistical only) This localization is consistent with Swift observation (Palmer et al., GCN 41781; Beardmore et al., GCN 41784). The time-averaged spectrum from T0 - 5 s to T0 + 40 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.52 +0.10/-0.12 and the cutoff energy, parameterized as Epeak, is 330 +180/-80 keV. The event fluence (10-1000 keV) in this time interval is (3.52 +0.25/-0.32)E-05 erg/cm^2. The 'Amati' relation diagram of GRB 250911A is shown at: https://www.bursthub.cn//admin/static/gecambgrb250911A_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/41813. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39878] GRB 250911A: Swift-BAT refined analysis
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41812 SUBJECT: GRB 250911A: Swift-BAT refined analysis DATE: 25/09/12 10:16:27 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> D. M. Palmer (LANL), S. D. Barthelmy (GSFC), R. Gupta (GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+200 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250911 A (trigger #1348587) (Klingler, et al., GCN Circ. 41781). The BAT ground-calculated position is RA, Dec = 263.752, -16.841 deg which is RA(J2000) = 17h 35m 00.6s Dec(J2000) = -16d 50' 28.0" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 29%. The mask-weighted BAT light curve shows two emission episodes (a precursor followed by main emission) separated by quiescent gap of ~ 80 sec. T90 (15-350 keV) is 128.42 +- 87.23 sec (estimated error including systematics). The time-averaged spectrum from T-1.35 to T+147.24 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.00 +- 0.20, and Epeak of 170.5 +- 84.5 keV (chi squared 56.83 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.5 +- 0.0 x 10^-05 erg/cm2 and the 1-sec peak flux measured from T+103.94 sec in the 15-150 keV band is 8.6 +- 0.6 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.35 +- 0.05 (chi squared 66.73 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1348587 View this GCN Circular online at https://gcn.nasa.gov/circulars/41812. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39877] EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41811 SUBJECT: EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84 DATE: 25/09/12 09:59:04 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> D. B. Malesani (DAWN/NBI and Radboud), A. J. Levan (Radboud and Warwick), G. Corcoran (UCD), R. A. J. Eyles-Ferris (Leicester), P. G. Jonker (Radboud), A. Martin-Carrillo (UCD), A. L. Cabrera Lavers (GTC), D. Reverte-Payá (GTC), A. Pérez-Romero (GTC) report for a larger collaboration: We observed the afterglow (Quirola-Vasquez et al., GCN 41790; Angulo et al., GCN 41793; Lai et al., GCN 41801; Evans et al., GCN 41802; Moskvitin & Spiridonova, GCN 41805; Ma et al., GCN 41807) of EP250911a (Liang et al. GCN 41788; Liang et al., GCN 41809) using the Gran Telescopio Canairas (GTC) equipped with the OSIRIS+ instrument. In a sequence of images taken in the r and z filters (mean times 13.97 and 14.12 hr after the trigger time, respectively), we measure magnitudes r = 22.0 +/- 0.1, z = 21.4 +/- 0.1 (all AB, calibrated against nearby Pan-STARRS objects, and not corrected for Galactic extinction). A sequence of 4 spectra with 1200 s exposure time each was obtained using the R1000B grism, covering the wavelength range 3700-7700 AA (mean time 15.4 hr after trigger). Inspection of the combined spectrum shows a weak continuum. A broad trough is observed around 5890 AA, which is interpreted as a DLA feature at a redshift z ~ 3.84. This is confirmed by the detection of a few metal absorption lines at a consistent redshift, among which we identify S II / Si II 1260, O II / Si II 1303, C II 1334, Si IV 1394, C IV 1548,1550. We also detect a continuum break around 4400 AA, which corresponds to the Lyman limit at this redshift. Note that, despite some temporal and spatial proximity, this redshift is inconsistent with the distance (~1.1 Gpc) derived for the LVK GW source S250911ac (LVK collaboration, GCNs 41786, GCN 41795), excluding an association between the two events. View this GCN Circular online at https://gcn.nasa.gov/circulars/41811. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39876] LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41810 SUBJECT: LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate DATE: 25/09/12 07:24:18 GMT FROM: Trang Nguyen <trang.nguyen(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S250912f during real-time processing of data from LIGO Livingston Observatory (L1) and Virgo Observatory (V1) at 2025-09-12 06:40:08.840 UTC (GPS time: 1441694426.840). The candidate was found by the GstLAL [1] and SPIIR [2] analysis pipelines. S250912f is an event of interest because its false alarm rate, as estimated by the online analysis, is 2.9e-13 Hz, or about one in 1e5 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S250912f The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [3] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [3] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (44.0, 88.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [4], distributed via GCN and SCiMMA notices about 27 seconds after the candidate event time. * bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [4], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is 393 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2870 +/- 784 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [2] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [3] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [4] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/41810. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39875] EP250911a: refined analysis of the EP-WXT and EP-FXT observations
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41809 SUBJECT: EP250911a: refined analysis of the EP-WXT and EP-FXT observations DATE: 25/09/12 05:02:03 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. F. Liang (PMO), Q. Y. Wu, W. D. Zhang(NAO, CAS) on behalf of the Einstein Probe (EP) team: The fast X-ray transient EP250911a triggered the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Liang et al., GCN 41788), and followed by Swift/XRT (Evans et al., GCN 41802) and several optical telescopes (Quirola-Vasquez et al., GCN 41790 , Angulo et al., GCN 41793, Lai et al., GCN 41801, Moskvitin et al., GCN 41805, Ma et al., GCN 41807). The refined analysis of the WXT data shows that the event started at T0=2025-09-11T08:57:55 (UTC) and lasted for 34 s with the peak flux of 9.3 x 10^(-9) erg/s/cm^2, before the observation was interrupted by the autonomous follow-up observation. The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 4.79 x 10^20 cm^-2 and a photon index of 0.77 (-/+0.95). The derived average unabsorbed 0.5-4 keV flux is 3.4 (-1.5/+3.1) x 10^(-9) erg/s/cm^2. The autonomous observation by the Follow-up X-ray Telescope (FXT) was performed at 2025-09-11T09:03:21 (UTC), about six minutes after T0. The exposure time of this observation is 3856 s. The on-ground analysis shows that an uncatalogued source was detected at R.A., Dec. = 357.5194, 29.2999 deg (J2000) with an uncertainty of about 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 equivalent hydrogen column density of 4.79 x 10^20 cm^-2 and a photon index of 2.02 (-/+0.22). The derived average unabsorbed 0.5-10 keV flux is 7.5 (-1.1/+1.4) x 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/41809. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39874] GRB 250910B: SVOM/GRM observation
by GCN Circulars 12 Sep '25

12 Sep '25

TITLE: GCN CIRCULAR NUMBER: 41808 SUBJECT: GRB 250910B: SVOM/GRM observation DATE: 25/09/12 04:13:28 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Jean-Luc Atteia (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a burst GRB 250910B (SVOM trigger reference: sb25091008) at 2025-09-10T18:52:06.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #41778). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 10.0 +4.5/-1.5 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250910B.png In addition, the position of this burst, as determined by Fermi/GBM (RA = 80.2, Dec = -46.4, GCN #41778), is located at about 54 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. ECLAIRs was not collecting data at the time of this burst. With the localization from Fermi/GBM, the time-averaged spectrum from T0-3 to T0+8.5 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.75 +0.12/-0.11 and the cutoff energy, parameterized as Epeak, is 218 +29/-22 keV. The event fluence (10-1000 keV) in this time interval is (5.77 +0.38/-0.36)E-06 erg/cm^2. The 'Amati' relation diagram of GRB 250910B is shown at: https://www.bursthub.cn//admin/static/svgrb250910B_amati.png 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 point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/41808. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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