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[vsnet-grb-info 43532] Fermi GRB 260808A: Global MASTER-Net observations report
by GCN Circulars 08 Aug '26

08 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45314 SUBJECT: Fermi GRB 260808A: Global MASTER-Net observations report DATE: 26/08/08 04:46:20 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), M. Segura, 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-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 260808A ( Fermi GBM team, GCN 45313) errorbox 99 sec after notice time and 136 sec after trigger time at 2026-08-08 02:53:58 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 68 deg. The sun altitude is -61.1 deg. The galactic latitude b = -39 deg., longitude l = 84 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3463356 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 152 | 2026-08-08 02:53:58 | MASTER-OAFA | (22h 48m 26.72s , +15d 27m 39.0s) | C | 30 | 17.9 | 188 | 2026-08-08 02:54:35 | MASTER-OAFA | (22h 48m 26.71s , +15d 27m 41.6s) | C | 30 | 18.1 | 229 | 2026-08-08 02:55:11 | MASTER-OAFA | (22h 48m 26.79s , +15d 27m 43.8s) | C | 40 | 18.1 | 281 | 2026-08-08 02:55:58 | MASTER-OAFA | (22h 48m 26.78s , +15d 27m 46.4s) | C | 50 | 18.4 | 342 | 2026-08-08 02:56:53 | MASTER-OAFA | (22h 48m 26.83s , +15d 27m 49.2s) | C | 60 | 18.5 | 641 | 2026-08-08 03:01:23 | MASTER-OAFA | (22h 46m 41.95s , +14d 00m 48.5s) | C | 120 | 19.1 | 777 | 2026-08-08 03:03:29 | MASTER-OAFA | (22h 46m 41.99s , +14d 00m 54.5s) | C | 140 | 19.2 | 938 | 2026-08-08 03:05:55 | MASTER-OAFA | (22h 46m 41.94s , +14d 01m 00.1s) | C | 170 | 19.3 | 1060 | 2026-08-08 03:08:52 | MASTER-OAFA | (22h 46m 41.89s , +14d 01m 04.3s) | C | 60 | 18.8 | 1126 | 2026-08-08 03:09:58 | MASTER-OAFA | (22h 46m 41.85s , +14d 01m 06.4s) | C | 60 | 18.9 | 1191 | 2026-08-08 03:11:03 | MASTER-OAFA | (22h 46m 41.82s , +14d 01m 09.3s) | C | 60 | 18.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/45314. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43531] GRB 260808A: Fermi GBM Final Real-time Localization
by GCN Circulars 08 Aug '26

08 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45313 SUBJECT: GRB 260808A: Fermi GBM Final Real-time Localization DATE: 26/08/08 03:02:15 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 02:51:42 UT on 8 Aug 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260808A (trigger 807850307.310674 / 260808119). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 341.8, Dec = 14.1 (J2000 degrees, equivalent to J2000 22h 47m, 14d 05'), with a statistical uncertainty of 2.2 degrees. The angle from the Fermi LAT boresight is 72.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260808119/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260808119/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260808119/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45313. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43530] EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
by GCN Circulars 07 Aug '26

07 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45312 SUBJECT: EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh DATE: 26/08/07 20:52:13 GMT FROM: akashjanaki98(a)gmail.com Akash Anumarlapudi (UNC CH), Robert Stein (UMD), Tomas Ahumada (NOIRLab), Aleksandra Bochenek (LJMU), Mansi Kasliwal, Lin Yan (Caltech), Michael W. Coughlin, Michael C. Davis (UMN), D. Y. Li, C.C.Jin, W. Yuan (NAO, CAS) report, on behalf of the ZTF collaboration. We report the serendipitous detection of ZTF26abmjjnm/AT 2026yeh by the Zwicky Transient Facility (Bellm et al. 2019, Graham et al. 2019). ZTF26abmjjnm is the optical counterpart to the X-ray transient EP260806a (GCN #45299), previously detected by GCNs #45300, #45302, #45303, #45304, #45306. It was first observed by ZTF at T0+12 hrs, resulting in detections in g,r bands. With g = 18.69 +/- 0.09 AB and r = 18.93 +/- 0.09 AB the source appears blue. Previous observations, roughly 4 days prior, resulted in non-detection at the location of ZTF26abmjjnm with g, r > 19.9 AB. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; University of Wisconsin at Milwaukee, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan; Operations are conducted by Caltech's Optical Observatory (COO) and Caltech/IPAC. View this GCN Circular online at https://gcn.nasa.gov/circulars/45312. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43529] GCN Announcement: LVK Notices Exclusively Available in JSON over Kafka, Updated CHIME Notices, and Schema v7.2.3
by GCN Announcements 07 Aug '26

07 Aug '26

The GCN Team announces updates to LVK and CHIME Notices and a schema release. LVK Notices Exclusively Available in JSON over Kafka As of July 8, 2026, the LIGO-Virgo-KAGRA (LVK) collaboration has ceased sending gravitational wave alerts in the VOEvent format to GCN Classic (https://gcn.gsfc.nasa.gov) The LVK VOEvent alerts were converted to all other GCN Classic formats and distribution methods (text via email and binary via socket connection). As a result, this change also disables all legacy LVK formats (text, binary, VOEvent) distributed over Kafka and email. GCN now distributes LVK Notices exclusively as JSON over Kafka. The LVK Public Alerts User Guide (https://emfollow.docs.ligo.org/userguide/) has been updated to provide information on the alert system that will be deployed in the next observation run (IR1) that is expected to start in late 2026 (https://observing.docs.ligo.org/plan/) To receive GCN Notices on LVK during IR1, please subscribe to JSON-format Notices on the Kafka topic igwn.gwalert (https://gcn.nasa.gov/docs/notices/consuming) At this time, these Notices are only available via Kafka, not email. Updated CHIME Notices CHIME is now distributing retractions of their FRB Notices on the topic gcn.notices.chime.frb, and has updated the example added in Schema v7.2.1 (https://gcn.nasa.gov/docs/schema/stable/gcn/notices/chime/frb.schema.json) Schema v7.2.3 GCN Schema v7.2.3 is available with recent changes including updated Notice examples (Release Notes; https://github.com/nasa-gcn/gcn-schema/releases/tag/v7.2.3) For more details on this new feature and an archive of GCN news and announcements, see https://gcn.nasa.gov/news. For questions, issues, or bug reports, please contact us via: - Contact form: https://gcn.nasa.gov/contact - GitHub issue tracker: https://github.com/nasa-gcn/gcn.nasa.gov/issues --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43528] IceCube Alert 260807A: Global MASTER-Net observations report
by GCN Circulars 07 Aug '26

07 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45311 SUBJECT: IceCube Alert 260807A: Global MASTER-Net observations report DATE: 26/08/07 18:52:39 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), M. Segura, 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 [1] located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the IceCube Alert 260807A (trigger No 68892416,21h 41m 28.80s , +00d 04m 12.0s, R=2.88) errorbox 45032 sec after notice time and 45086 sec after trigger time at 2026-08-07 18:36:08 UT, with upper limit up to 19.8 mag. The observations began at zenith distance = 53 deg. The sun altitude is -19.4 deg. The galactic latitude b = -37 deg., longitude l = 56 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3462157 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 45117 | 2026-08-07 18:36:08 | MASTER-Tunka | (21h 40m 12.04s , -00d 17m 44.0s) | C | 60 | 18.9 | 45190 | 2026-08-07 18:37:21 | MASTER-Tunka | (21h 40m 11.54s , -00d 16m 46.4s) | C | 60 | 19.7 | 45264 | 2026-08-07 18:38:36 | MASTER-Tunka | (21h 40m 17.87s , -00d 17m 49.6s) | C | 60 | 19.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/45311. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43527] IceCube-260805A: One candidate from the Zwicky Transient Facility
by GCN Circulars 07 Aug '26

07 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45310 SUBJECT: IceCube-260805A: One candidate from the Zwicky Transient Facility DATE: 26/08/07 16:29:17 GMT FROM: akshay.eranhalodi(a)desy.de Akshay Eranhalodi (DESY), Robert Stein (JSI), Cristobal Zilleruelo Cañas (DESY), 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-260805A (IceCube Collaboration, GCN 45294) 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 2026-08-06 10:23 UTC, approximately 20.4 hours after event time. We covered 65.4% (1.0 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 one transient candidate by our pipeline, lying within the 90.0% localization of the skymap. +--------------------------------------------------------------------------------+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr | +--------------------------------------------------------------------------------+ | ZTF26aaskzvj | AT 2026jrc | +60.57411872 | +25.81342036 | g | 20.937 | 0.182 | +--------------------------------------------------------------------------------+ ZTF26aaskzvj/AT 2026jrc was first detected on 2026-04-15, and is a SN-like transient associated with a nearby galaxy in NED at z=0.0192 (~85 Mpc). The transient is only marginally detected with forced photometry at the neutrino arrival time. The source appears to have peaked 100 days ago at M<-18 in r-band, and is now much fainter at M=-15.4 as of last week. We encourage spectroscopic follow-up to determine its nature and asses potential high-energy neutrino emission scenarios. ZTF and GROWTH are worldwide collaborations comprising Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan; OKC, Sweden; DZA, Germany. 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). Alert filtering is performed with the nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ). View this GCN Circular online at https://gcn.nasa.gov/circulars/45310. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43526] GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
by GCN Circulars 07 Aug '26

07 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45309 SUBJECT: GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit DATE: 26/08/07 16:17:10 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> Antonio de Ugarte Postigo (LAM), Enrique Moreno Méndez (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Alan M. Watson (UNAM), Chao Wu (NAOC) and Rui-Zhi Li (YNAO) report: We imaged the field of the SVOM GRB 260807A (Xie et al., GCN Circ. 45308) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2026-08-07 11:43:34 to 11:47:16 UTC (from 0.7266 to 0.8050 hours after the trigger) and obtained 4x60 seconds of exposure in the z band before the end of the night. The data were reduced and coadded with the COLIBRÍ pipeline and analyzed with the ASU pipeline of COLIBRÍ and with STDWeb (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1r catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any convincing new source within the ECLAIRs error circle (Xie et al., GCN Circ. 45308) down to the following 5-sigma limit: z > 20.0 We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/45309. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43525] GRB 260807A: SVOM possible detection of a faint burst
by GCN Circulars 07 Aug '26

07 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45308 SUBJECT: GRB 260807A: SVOM possible detection of a faint burst DATE: 26/08/07 11:45:48 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Wenjin Xie, Donghua Zhao(NAOC), Hui Yang, Laurent Bouchet (IRAP), Ruizhi Li (YNAO), Chao Wu (NAOC) report on behalf of the SVOM mission team: At 2026-08-07T11:00:20 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260807A (SVOM burst-id sb26080703). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Count-Rate Trigger (CRT), which produced a sequence of 1 alert. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 7 in the [8-120] keV energy band over a time window of 20.40 seconds starting at 2026-08-07T10:59:59. The localization of the best alert is R.A., Dec. 16.1480, 44.7752 degrees: R.A. (J2000) = 1h04m35.51s Dec. (J2000) = 44d46m30.57s with a 90% confidence level (C.L.) radius of 11.18 arcmin (including systematic error of 2 arcmin added in quadrature). Due to the detection significance being below the slew threshold and the sun angle constraint, no immediate slew was performed on this burst. No X-ray observation could be performed by SVOM/MXT for the time being. No optical observation could be performed by SVOM/VT for the time being. 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 Chao WU: cwu(a)bao.ac.cn Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/45308. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43524] IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 07 Aug '26

07 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45307 SUBJECT: IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 26/08/07 10:05:17 GMT FROM: Cristobal Zilleruelo Cañas at DESY <cristobal.zilleruelo.canas(a)desy.de> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 26-08-07 at 06:04:41.70 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. Documentation regarding the alert streams and their astrophysical purity can be found here: https://gcn.nasa.gov/missions/icecube. This alert has an estimated false alarm rate of 3.913 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/142963_68892416.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 26-08-07 Time: 06:04:41.70 UT RA: 325.37 (+4.26/-7.82 deg 90% PSF containment) J2000 Dec: 0.07 (+0.98/-1.77 deg 90% PSF containment) J2000 As announced in GCN Circular 43419 (https://gcn.nasa.gov/circulars/43419) IceCube alert notices for high-energy track alerts are now also streamed via Kafka. IceCube Gold/Bronze track alerts are available on the Kafka topic 'gcn.notices.icecube.gold_bronze_track_alerts'. The probability distribution of the true neutrino direction, allowing the extraction of precise 90% containment regions around the best-fit direction, is now available for revised reconstruction of high-energy track alerts. The corresponding sky map is distributed as a FITS file and follows the explicit naming convention IceCube-YYMMDDX, where YYMMDD indicates the date of the event and X is a letter distinguishing multiple alerts on the same day. The download link is provided through the GCN schema distributed via Kafka. Detailed documentation describing the alert distribution, schemas, and probability maps is available at: https://gcn.nasa.gov/missions/icecube. 7 gamma-ray sources from the Fermi FL16Y catalog are located within the 90% uncertainty region of this event. The closest source is FL16Y J2136.6+0041 at RA = 324.150° and Dec = 0.685° (J2000), with an angular separation of 1.365° from the best-fit event position. We report here sources within the 90% confidence contour available in the multi-order probability map, rather than those selected using the simplified rectangular error-box reported in this Circular. 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/45307. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43523] EP260806a: COLIBRÍ optical observations
by GCN Circulars 07 Aug '26

07 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45306 SUBJECT: EP260806a: COLIBRÍ optical observations DATE: 26/08/07 10:01:00 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> Antonio de Ugarte Postigo (LAM), Enrique Moreno Méndez (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Alan M. Watson (UNAM) report: We imaged the field of the EP260806a (Li et al., GCN Circ. 45299) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-08-07 05:27:53 to 06:26:13 UTC (from 6.423 to 7.396 hours after the trigger) and obtained 16 minutes of exposure in the z and y filters. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS catalog, is in the AB system, and is not corrected for Galactic extinction. After subtracting the template, we clearly detected the optical counterpart (He et al., GCN Circ. 45300; de Ugarte Postigo et al. GCN Circ. 45302; Eyles-Ferris GCN Circ. 45303; Ma et al. GCN Circ. 45304) at a preliminary magnitude of: z = 19.44 +/- 0.04 Further observations are ongoing. We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/45306. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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