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

[vsnet-grb-info 40524] GRB 251025B: Swift-XRT afterglow detection
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42445 SUBJECT: GRB 251025B: Swift-XRT afterglow detection DATE: 25/10/25 19:52:19 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), S. Lanava (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of GRB 251025B. We searched for X-ray sources in 1.7 ks of Photon Counting (PC) mode data obtained between T0+2.8 ks and T0+4.5 ks. An uncatalogued X-ray source is detected within the estimated 3-sigma SVOM/ECLAIRs error region (473 arcsec) and is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 1712 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 29.53107, +30.30373 which is equivalent to: RA (J2000): 01h 58m 07.46s Dec(J2000): +30d 18' 13.4" with an uncertainty of 2.7 arcsec (radius, 90% confidence). This source is 1.25 arcsec from the SVOM/C-GFT position (Wu et al., GCN Circ. 42438) and 37 arcsec from the SVOM/MXT position (Hussein et al., GCN Circ. 42437). At present, the X-ray source shows no evidence of fading. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.00 (+0.27, -0.25). The best-fitting absorption column is 1.9 (+0.9, -0.8) x 10^21 cm^-2, in excess of the Galactic value of 5.6 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.9 (+0.9, -0.8) x 10^21 cm^-2 Galactic foreground: 5.6 x 10^20 cm^-2 Excess significance: 2.8 sigma Photon index: 2.00 (+0.27, -0.25) The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/03000153. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00044. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42445. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40523] GRB 251024A: Swift-BAT refined analysis
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42444 SUBJECT: GRB 251024A: Swift-BAT refined analysis DATE: 25/10/25 19:40:31 GMT FROM: Amy <yarleen(a)gmail.com> T. Sakamoto (AGU), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC) (i.e. the Swift-BAT team): Using the data set from T-240 to T+613 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251024A (trigger #1406589) (Moss et al., GCN Circ. 42426). The BAT ground-calculated position is RA, Dec = 306.666, -68.576 deg which is RA(J2000) = 20h 26m 39.7s Dec(J2000) = -68d 34' 34.3" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 84%. The mask-weighted light curve shows a weak pulse structure that starts at ~T+1 s and peaks at ~T+3 s. The main pulse structure ends at ~T+25 s, and there are some tail emissions that last till ~T+100 s. T90 (15-350 keV) is 82.66 +- 23.27 sec (estimated error including systematics). The time-averaged spectrum from T+1.16 to T+97.28 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.68 +- 0.30. The fluence in the 15-150 keV band is 6.5 +- 1.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+2.16 sec in the 15-150 keV band is 0.5 +- 0.2 ph/cm2/sec. 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/1406589 View this GCN Circular online at https://gcn.nasa.gov/circulars/42444. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40522] IceCube Alert 251025.57: Global MASTER-Net observations report
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42443 SUBJECT: IceCube Alert 251025.57: Global MASTER-Net observations report DATE: 25/10/25 19:39:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the IceCube Alert 251025.57 (trigger No 18513107,09h 42m 47.28s , +15d 19m 48.0s, R=1.19) errorbox 16456 sec after notice time and 16501 sec after trigger time at 2025-10-25 18:22:54 UT, with upper limit up to 17.6 mag. The observations began at zenith distance = 80 deg. The sun altitude is -47.0 deg. The galactic latitude b = 45 deg., longitude l = 219 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3023371 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 16531 | 2025-10-25 18:22:54 | MASTER-Tunka | (09h 42m 13.68s , +14d 52m 14.6s) | C | 60 | 17.6 | 16531 | 2025-10-25 18:22:54 | MASTER- | (09h 42m 26.98s , +14d 45m 50.3s) | C | 60 | 17.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42443. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40521] GRB 251024A: Swift-XRT refined Analysis
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42442 SUBJECT: GRB 251024A: Swift-XRT refined Analysis DATE: 25/10/25 18:09:15 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 4.4 ks of XRT data for GRB 251024A, from 113 s to 56.4 ks after the trigger. The data comprise 30 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The late-time light curve (from T0+4.5 ks) is consistent with a constant source of mean count rate 4.5e-01 ct/sec. A power-law fit gives an index of -0.14 (+0.15, -0.14). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.06 (+0.16, -0.11). The best-fitting absorption column is consistent with the Galactic value of 3.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.7 (+/-2.8) x 10^20 cm^-2 Galactic foreground: 3.7 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 2.06 (+0.16, -0.11) The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01406589. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42442. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40520] GRB 251025A (sb25102501): stellar flare confirmed
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42441 SUBJECT: GRB 251025A (sb25102501): stellar flare confirmed DATE: 25/10/25 17:15:53 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Zhe Kang (CHO), Chao WU (NAOC), 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), Z.M. Wang (BNU), W.J. Tan (IHEP) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 251025A (sb25102501) detected by SVOM/ECLAIRs (wang et al., GCN 42432) with LATIOS on SVOM/C-GFT. Observations started at 2025-10-25T09:36:54 UTC, ~92 seconds after the trigger. A sequence of images in the g, r, and i bands was obtained. The likely flaring star RX J2350.0+2659, reported by Li et al. (GCN 42435), is clearly detected. The source exhibited a fade in the i band from 9.68 to 11.38 mag over ~40 min, starting around T0+93 sec. Our observations confirm that this is a stellar flare. We thank the observation assistants Hongxu Xuan and Bowen Li 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/42441. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40519] GRB 251025B: SVOM/VT optical observations with VHF data
by GCN Circulars 25 Oct '25

25 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 19.15 +/-0.02 523 sec 300 sec VT_B 18.61 +/-0.01 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 40518] GRB 251025B: MASTER OT detection
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42439 SUBJECT: GRB 251025B: MASTER OT detection DATE: 25/10/25 16:28:10 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> O.Gress, N.Budnev (Irkutsk State University), V. Lipunov, P.Balanutsa, I.Panchenko, A.Kuznetsov, G.Antipov, E.Gorbovskoy, K.Zhirkov, N.Tiurina, A.Sankovich, Ya.Kechin, A.Chasovnikov, V.Topolev, D.Vlasenko, V.Senik, D.Vlasenko, V.Shumkov, K.Vetrov, Yu. Tselik(Lomonosov MSU, SAI, Moscow), R.Podesta, C.Francile, F. Podesta, E. Gonzalez (OAFA, San Juan Uni.,Argentina); D.Buckley (SAAO, South Africa), O.Ershova (ISU, Irkutsk), A.Sosnovskij (CrAO RAS), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), V.M.Pillet, R.Rebolo Lopez (The Instituto de Astrofisica de Canarias, Spain), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez,J.Martinez,A.R.Corella,L.H.Rodriguez (INAOE, Guillermo Haro Astrophysic Observatory, Mexico) MASTER Global Robotic Net [1-4] started Svom GRB 251025B (Hussein et al. GCN 42437, Ttrigger= 2025-10-25 14:24:05UT) at MASTER-Tunka and at MASTER-Kislovodsk. There is MASTER OT J015807.49+301814.0 with unfiltered m_OT=19.0 at at 2025-10-25 14:36:20 (mlim=20.5) Observation and reduction will be continued. This OT was discovered by SVOM (Chao Wu et al. GCN 42438, first image at 2025-10-25T14:25:38) [1] Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L [2] Lipunov et al. 2022, Universe, Vol. 8(5), id.271 [3] Lipunov et a. 2019, ARep, vol.63, 293 [4] Lipunov V., Kornilov V., Gorbovskoy E., Tiurina N., Kuznetsov A. 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics,Lomonosov MSU PRESS, 591pp. http://www.pereplet.ru/lipunov/625.html#625 View this GCN Circular online at https://gcn.nasa.gov/circulars/42439. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40517] GRB 251025B: SVOM/C-GFT optical counterpart detection
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42438 SUBJECT: GRB 251025B: SVOM/C-GFT optical counterpart detection DATE: 25/10/25 15:50:39 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),S.Hussein (IJCLab), M. Brunet (IRAP) report on behalf of the SVOM/C-GFT team: We observed the field of GRB 251025B (sb25102502) detected by SVOM/ECLAIRs (Hussein et al. GCN 42437) with LATIOS on SVOM/C-GFT. Observations started at 2025-10-25T14:25:38 UTC, ~93 seconds after the trigger. An uncatalogued optical source compared to PanStarrs1 catalogue is detected in our images within the SVOM/MXT localization error circle at: RA (J2000) = 01h58m07.49s = 29.53123 degrees Dec (J2000) = +30h18m14.5s = 30.30405 degrees with an uncertainty of ~0.5 arcsec. The magnitudes are: |[date-obs(mid-time)] | Mid_t-T0(s) | exposure time (s) | band | mag (AB) | mag_err| |--------------------|--------------|-------------------|------|----------|--------| | 2025-10-25T14:25:38| 98 | 10 | i | 17.49 | 0.12 | The photometry was calibrated against nearby Pan-STARRS1 stars and no correction for Galactic dust extinction was applied. The source exhibited ~1 mag decline in the i band over about 10 min. We propose that it is the optical counterpart of GRB 251025B. We thank the observation assistants Hongxu Xuan and Bowen Li 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/42438. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40516] GRB 251025B: SVOM detection of a burst
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42437 SUBJECT: GRB 251025B: SVOM detection of a burst DATE: 25/10/25 15:12:36 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> S. Hussein (IJCLab), M. Brunet (IRAP), U. Jacob (LUPM), D. Gotz (CEA), P. Maggi (ObAS), report on behalf of the SVOM mission team: At 2025-10-25T14:24:05 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251025B (SVOM burst-id sb25102502). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 13 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 17.67 in the [8-120] keV energy band over a time window of 10.20 seconds starting at 2025-10-25T14:24:00. The localization of the best alert is R.A., Dec. 29.5647, 30.2424 degrees (J2000) with a 90% confidence level (C.L.) radius of 4.80 arcmin (including systematic error of 2 arcmin added in quadrature). This burst was also detected by SVOM/GRM with a significance of 8.80. SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-10-25T14:27:11 UTC, 186 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 29.542, 30.308 degrees: R.A. (J2000) = 1h58m10.23s Dec. (J2000) = 30d18m32.2s with a 90% C.L. radius of 127.48 arcseconds. This location is 4.15 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the data will be published in a future circular. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Shaymaa Hussein: hussein(a)astro.uni-tuebingen.de. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42437. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40515] IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 25 Oct '25

25 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42436 SUBJECT: IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/10/25 14:59:09 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 25-10-25 at 13:47:53.26 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 2.3507 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/141518_18513107.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 25-10-25 Time: 13:47:53.26 UT RA: 145.63 (+0.88/-0.88 deg 90% PSF containment) J2000 Dec: 15.06 (+0.65/-0.62 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of the event. 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 View this GCN Circular online at https://gcn.nasa.gov/circulars/42436. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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