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

[vsnet-grb-info 40614] LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
by GCN Circulars 31 Oct '25

31 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42529 SUBJECT: LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate DATE: 25/10/31 19:29:26 GMT FROM: Dripta Bhattacharjee <dripta.bhattacharjee(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251031cq during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-10-31 18:59:15.906 UTC (GPS time: 1445972373.906). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], MLy [6], and PyCBC Live [7] analysis pipelines. S251031cq is an event of interest because its false alarm rate, as estimated by the online analysis, is 7e-10 Hz, or about one in 45 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251031cq 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%. [8] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [8] 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 (22.0, 44.0) 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 [9], distributed via GCN and SCiMMA notices about 24 seconds after the candidate event time. * bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [9], distributed via GCN and SCiMMA notices about 4 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 709 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2083 +/- 562 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] Marx et al. PRD 111, 042010 (2025) doi:10.1103/PhysRevD.111.042010 [2] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [3] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [4] 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 [5] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [6] Skliris et al. PRD 110, 104034 (2024) doi:10.1103/PhysRevD.110.104034 [7] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [8] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [9] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42529. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40613] GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
by GCN Circulars 31 Oct '25

31 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42528 SUBJECT: GRB 251031A: Swift/BAT-GUANO localization skymap of a burst DATE: 25/10/31 18:52:57 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 251031A onboard (T0: 2025-10-31T07:21:00.49 UTC, Fermi Trig 783588065) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 8.4 in a 16.384 s analysis time bin, starting at T0 + 8.192 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 8,620 deg2 and the 50% credible area is 269 deg2. The integrated probability inside the coded field of view is 1%. The NITRATES skymap is consistent with the Fermi localization reported in the final position notice (GCN 42525). The combined Fermi/GBM+NITRATES 90% credible area is 168 deg2 and the 50% credible area is 47 deg2. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=783588097/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/783588097/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/783588097/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=783588097 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/42528. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40612] Konus-Wind detection of GRB 251028A
by GCN Circulars 31 Oct '25

31 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42527 SUBJECT: Konus-Wind detection of GRB 251028A DATE: 25/10/31 16:09:13 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 251028A (Ferm-GBM detection: The Fermi GBM team, GCN 42497; Veres and Meegan, GCN 42520; BALROG localization: Preis & Greiner, GCN 42499; MAXI-GSC detection: Sugai et al., GCN 42498; Glowbug detection: Cheung et al., GCN 42506; SVOM-GRM detection: Guo et al., GCN 42522; GECAM-B detection: Guo et al., GCN 42523) triggered Konus-Wind at T0=12396.343 s UT (03:26:36.343). The burst light curve starts with a possible rise of a weak emission at ~T0-67 s, which, at ~T0-5.5 s, evolves into the main multi-peaked emission episode with a duration of ~38 s. The emission is seen up to ~5 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251028_T12396/ As observed by Konus-Wind, the burst had the total fluence of 3.95(-0.25,+0.27)x10^-5 erg/cm2, and the 64-ms peak flux, measured from T0+19.568 s, of 3.17(-0.62,+0.64)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the main episode (measured from T0 to T0+33.024 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.70(-0.12,+0.13), the high energy photon index beta = -2.81(-0.39,+0.22), the peak energy Ep = 229(-15,+16) keV (chi2 = 92/97 dof). The spectrum near the maximum count rate (measured from T0+16.640 to T0+24.832 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.31(-0.20,+0.22), the high energy photon index beta = -3.22(-1.23,+0.42), the peak energy Ep = 217(-15,+17) keV (chi2 = 77/82 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/42527. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40611] GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
by GCN Circulars 31 Oct '25

31 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42526 SUBJECT: GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306) DATE: 25/10/31 07:43:38 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 783588065 at 07:21:00 on 31 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) = 188.3 deg Decl.(2000.0) = -17.9 deg The 1 sigma statistical error radius is 2.8 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB251031306/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251031306/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251031306/json View this GCN Circular online at https://gcn.nasa.gov/circulars/42526. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40610] GRB 251031A: Fermi GBM Final Real-time Localization
by GCN Circulars 31 Oct '25

31 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42525 SUBJECT: GRB 251031A: Fermi GBM Final Real-time Localization DATE: 25/10/31 07:31:22 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 07:21:00 UT on 31 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251031A (trigger 783588065.486224 / 251031306). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 190.3, Dec = -17.6 (J2000 degrees, equivalent to J2000 12h 41m, -17d 36'), with a statistical uncertainty of 3.3 degrees. The angle from the Fermi LAT boresight is 49.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251031306/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251031306/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251031306/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42525. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40609] GRB 251025C: SVOM/GRM observation
by GCN Circulars 30 Oct '25

30 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42524 SUBJECT: GRB 251025C: SVOM/GRM observation DATE: 25/10/30 17:03:31 GMT FROM: tanwj(a)ihep.ac.cn SVOM/GRM team: Wen-Jun Tan, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Sebastien Guillot (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 251025C (SVOM burst-id sb25102505) at 2025-10-25T23:08:41.000 (T0), which is also detected by Fermi/GBM (Fermi/GBM team, GCN # 42449), CALET (S. Torii, et al. GCN # 42467), AstroSat CZTI (A. Arya, et al. GCN # 42469) and Glowbug (R. Woolf, et al. GCN # 42490). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a significant peak followed by weak emission with a T90 of 30.4 +13.2/-12.6 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251025C.png In addition, the position of this burst, as determined by Fermi/GBM (RA = 170.7, Dec = 54.9 , GCN #42449), is located at about 89 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization given by Fermi/GBM, the time-averaged spectrum from T0-2 to T0+30 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.97 +0.16/-0.14 and the cutoff energy, parameterized as Epeak, is 1450 +680/-440 keV. The event fluence (10-1000 keV) in this time interval is (1.06 +0.09/-0.27)E-05 erg/cm^2. The localization of GRB 251025C in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251025C_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: Wen-Jun Tan (IHEP)(tanwj(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42524. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40608] GRB 251028A: GECAM-B detection
by GCN Circulars 30 Oct '25

30 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42523 SUBJECT: GRB 251028A: GECAM-B detection DATE: 25/10/30 15:46:39 GMT FROM: guohx(a)ihep.ac.cn Hao-Xuan Guo, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by a long burst, GRB 251028A, at 2025-10-28T03:26:40.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#42497, GCN#42499), MAXI/GSC (MAXI team, GCN#42498), Glowbug (C.C. Cheung et al., GCN#42506) and SVOM/GRM (SVOM/GRM team, SVOM/ECLAIRs team, GCN#42522). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 38 +4/-5 s. shi The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251028A.png The time-averaged spectrum from T0-10 s to T0+45 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.05 +0.11/-0.11 and the cutoff energy, parameterized as Epeak, is 259 +38/-25 keV. The event fluence (10-1000 keV) in this time interval is (3.12 +0.20/-0.17)E-05 erg/cm^2. The 'Amati' relation diagram of GRB 251028A is shown at: https://www.bursthub.cn//admin/static/gecambgrb251028A_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/42523. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40607] GRB 251028A: SVOM/GRM observation
by GCN Circulars 30 Oct '25

30 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42522 SUBJECT: GRB 251028A: SVOM/GRM observation DATE: 25/10/30 13:47:16 GMT FROM: Haoxuan Guo <skyairsama(a)gmail.com> SVOM/GRM team: Hao-Xuan Guo, Chen-Wei Wang, Zheng-Hang Yu, Chao Zheng,, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)SVOM/ECLAIRs team: Report on behalf of the SVOM team: SVOM/ECLAIRs team: Sebastien Guillot (IRAP) SVOM/GRM was triggered in-flight by a burst GRB 251028A (SVOM trigger reference: sb25102801) at 2025-10-28T03:26:37.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#42497, GCN#42499), MAXI/GSC (MAXI team, GCN#42498) and Glowbug (C.C. Cheung et al., GCN#42506). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple peaks with a T90 of 31.0 +6.5/-3.0 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251028A.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 149.5, DEC= 20.2, GCN#42497), is located at about 157 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view, but this burst still clearly detected by ECLAIRs due to the reflection of the Earth atmosphere. With this localization, the time-averaged spectrum from T0-10 to T0+45 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.31 +0.14/-0.16 and the cutoff energy, parameterized as Epeak, is 345 +107/-64 keV. The event fluence (10-1000 keV) in this time interval is (4.56 +0.24/-0.27)E-5 erg/cm^2. The localization of GRB 251028A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251028A_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: Hao-Xuan Guo (IHEP)(guohx(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42522. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40606] IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
by GCN Circulars 29 Oct '25

29 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42521 SUBJECT: IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility DATE: 25/10/29 23:11:01 GMT FROM: Robert David Stein at JSI <rdstein(a)umd.edu> Akshay Eranhalodi (DESY), Robert Stein (JSI), Jannis Necker (Leiden University) and Anna Franckowiak (Ruhr University Bochum) report: On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: As part of the ZTF neutrino follow up program (Stein et al. 2023), we observed the localization region of the neutrino event IceCube-251025A (Zegarelli et. al, GCN 42436) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2025-10-26 11:02 UTC, approximately 21.2 hours after event time. We covered 98.9% (2.1 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019) . We are left with the following high-significance transient candidates by our pipeline, all lying within the 90.0% localization of the skymap. ±–––––––––––––––––––––––––––––––––––––––-+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr | ±–––––––––––––––––––––––––––––––––––––––-+ | ZTF25acammho | AT 2025abwy | 144.8380039 | +15.6961873 | g | 21.13 | 0.21 | | ZTF25acamsai | AT 2025abtz | 146.0869065 | +14.6023944 | r | 20.75 | 0.12 | ±–––––––––––––––––––––––––––––––––––––––-+ Amongst our candidates, we find two unclassified transients of potential interest. ZTF25acammho/AT 2025abwy was inititally detected on 2025-10-03 in r-band, and was then redetected in our ToO observations three weeks later. The source appears to be hostless, with a current magnitude of 21.13. ZTF25acamsai/AT 2025abtz was first detected on 2025-10-22, and appears coincident with a host galaxy of photometric redshift z=0.2. This would imply a magnitude of M=-19.5. The source appears to be blue. We encourage spectrscopic observations to confirm the nature of these two transients. In addition, we also recover one known supernova, ZTF25abvepyj/SN2025zno. The source was first detected by ZTF on 2025-10-02, and is classified as Type Ia Supernova at a redshift of 0.064. Type Ia supernovae are not predicted to be significant neutrino emitters, so we conclude that this source is unrelated to the neutrino. We further find one likely AGN (ZTF19aaixfxw) with W1-W2=0.8. This source does not display any evidence of flaring coincident with the neutrino, and we see no reason to associate it with IC251025A. The neutrino localisation was also observed by DDOTI (Becerra et al., GCN 42457) who report no uncatalogued source with w > 20. These observations are consistent with our observations reported here. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA; WIS, Israel; OKC, Sweden; JSI/UMd, USA; DESY, Germany; TANGO, Taiwan; UW Milwaukee, USA; LANL, USA; TCD, Ireland; IN2P3, France. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019). View this GCN Circular online at https://gcn.nasa.gov/circulars/42521. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 40605] GRB 251028A: Fermi GBM Observation
by GCN Circulars 29 Oct '25

29 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42520 SUBJECT: GRB 251028A: Fermi GBM Observation DATE: 25/10/29 20:08:12 GMT FROM: Peter Veres at University of Alabama in Huntsville <veresp(a)gmail.com> P. Veres (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 03:26:31.86 UT on 28 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251028A (trigger 783314796/251028143) which was also detected by MAXI (Negoro et al. 2025, GCN 42498) and Glowbug (Cheung et al. 2025, GCN 42506). The Fermi GBM on-ground location is consistent with the MAXI position. The angle from the Fermi LAT boresight is 50 degrees. The GBM light curve consists of multiple overlapping pulses with a duration (T90) of about 30 s (50-300 keV). The time-averaged spectrum from T0 to T0+39.9 s is best fit by a Band function with Epeak = 244 +/- 14 keV, alpha = -0.91 +/- 0.03, and beta = -2.4 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (3.13 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+24 s in the 10-1000 keV band is 10.8 +/- 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/42520. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0