July 2026 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 43411] GRB 260722A: Fermi GBM Final Real-time Localization
by GCN Circulars 22 Jul '26

22 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45195 SUBJECT: GRB 260722A: Fermi GBM Final Real-time Localization DATE: 26/07/22 13:26:44 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 13:16:06 UT on 22 Jul 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260722A (trigger 806418971.769656 / 260722553). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 90.5, Dec = -40.4 (J2000 degrees, equivalent to J2000 06h 01m, -40d 23'), with a statistical uncertainty of 1.8 degrees. The angle from the Fermi LAT boresight is 18.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260722553/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260722553/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260722553/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45195. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43410] IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 22 Jul '26

22 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45194 SUBJECT: IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 26/07/22 08:50:23 GMT FROM: cristobal.zilleruelo.canas(a)desy.de The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 26-07-22 at 06:58:22.82 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 1.4973 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/142900_47091427.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 26-07-22 Time: 06:58:22.82 UT RA: 190.55 (+1.03/-1.33 deg 90% PSF containment) J2000 Dec: 31.0 (+0.67/-0.64 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. No known gamma-ray sources listed in the Fermi LAT 16-year Source List (FL16Y) are located within the 90% uncertainty region of this 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/45194. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43409] Fermi GBM trigger 806384210/260722151 is not a GRB
by GCN Circulars 22 Jul '26

22 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45193 SUBJECT: Fermi GBM trigger 806384210/260722151 is not a GRB DATE: 26/07/22 06:08:28 GMT FROM: Suman Bala at USRA <sumanbala2210(a)gmail.com> S. Bala (USRA) reports report on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 806384210/260722151 at 03:36:45.35 UT on 22 July 2026, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to solar flare." View this GCN Circular online at https://gcn.nasa.gov/circulars/45193. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43408] GRB 260721A: NuSTAR detection of prompt emission
by GCN Circulars 21 Jul '26

21 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45192 SUBJECT: GRB 260721A: NuSTAR detection of prompt emission DATE: 26/07/21 16:36:31 GMT FROM: Brian Grefenstette at Caltech/NuSTAR <bwgref(a)srl.caltech.edu> B. Grefenstette (Caltech) and G. Waratkar (Caltech) report on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group: The NuSTAR SINGS working group reports the detection of prompt emission from the long-duration GRB 260721A in both the NuSTAR CsI anti-coincidence shields. Details of the search algorithm will be described in a future paper. The NuSTAR SINGS algorithm, triggered at 2026-07-21 01:17:08 UTC, shows a detection of GRB 260721A, also detected by Konus-Wind (Svinkin, priv. Comm & GCN notices). The NuSTAR CsI shield data are recorded at 1 Hz. We detect a burst lasting for about 10-s. Offline analysis indicates that the burst first appeared in the NuSTAR data 6 to 7-s prior to the trigger time (with a non-barycenter corrected, offline T0 of roughly 2026-07-21T01:17:02). The peak count rate is ~2000-cps with a baseline rate of ~1000-cps during this time period. We do not see any evidence in the signal above 100 keV in the CZT detectors. Lightcurves and analysis for this GRB can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2026/260721A/ Information on NuSTAR SINGS can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/ NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. View this GCN Circular online at https://gcn.nasa.gov/circulars/45192. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43407] Konus-Wind detection of GRB 260714B
by GCN Circulars 21 Jul '26

21 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45191 SUBJECT: Konus-Wind detection of GRB 260714B DATE: 26/07/21 15:33:10 GMT FROM: Valentina Panteleeva at Ioffe Institute <panteleevav228(a)gmail.com> V. Panteleeva, D. Frederiks, A. Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 260714B (Fermi-GBM detection: The Fermi GBM team, GCN 45161; Fermi-LAT detection: The Fermi GBM team, GCN 45162; AstroSat-CZTI detection: Pathak et al., GCN 45163; GECAM-B detection: Ren et al., GCN 45174; SVOM-GRM detection: Ren et al., GCN 45176; Insight-HXMT-HE detection: Luo et al., GCN 45188) triggered Konus-Wind at T0=66206.858 s UT (18:23:26.858). The burst light curve shows a multipeaked structure which starts at ~T0-0.4 s and has a total duration of ~15.5 s. The emission is seen up to 2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260714_T66206/ As observed by Konus-Wind, the burst had the total fluence of 3.09(-0.20,+0.23)x10^-5 erg/cm2, and the 64-ms peak flux, measured from T0+2.640 s, of 1.39(-0.15,+0.16)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+15.360 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 = -1.07(-0.04,+0.04), the high energy photon index beta = -3.61(-6.39,+0.71), the peak energy Ep = 595(-44,+55) keV (chi2 = 122/94 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+7.168 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 = -0.94(-0.05,+0.05), the high energy photon index beta = -2.97(-1.36,+0.38), the peak energy Ep = 605(-51,+56) keV (chi2 = 66/79 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/45191. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43406] SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
by GCN Circulars 21 Jul '26

21 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45190 SUBJECT: SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare DATE: 26/07/21 05:16:55 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, Y. N. Ma, C. Wu, Y. L. Qiu, L. P. Xin, Z. H. Yao, J. R. Xu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC) and J. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team. SVOM/VT performed observations with automatic slew to the field of X-ray transient sb26071506 triggered by SVOM/ECLAIRs (Cangemi et al., GCN 45169). The observations started at 2026-07-15T16:28:06 UTC, i.e., 327 sec post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously. The high-proper motion star V* AT Mic located within the errorbox of and MXT and ECLAIRs (Cangemi et al., GCN 45169) was saturated in both channels of VT. We performed photometry using the method described in Li et al. (2026, arXiv:2604.24266). Its brightness decreased in both channels, especially in VT_B band decayed from ~10.9 mag to ~11.2 mag in about 1.4 hours. This fading confirms this ECLAIRs trigger is related to the stellar flare. 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/45190. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43405] GRB 260705A: Retraction of optical counterpart
by GCN Circulars 20 Jul '26

20 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45189 SUBJECT: GRB 260705A: Retraction of optical counterpart DATE: 26/07/20 20:02:38 GMT FROM: James Freeburn at University of North Carolina at Chapel Hill <jamesfreeburn54(a)gmail.com> James Freeburn (UNC), Tomás Ahumada (NOIRLab), Jillian Rastinejad (UMD), Gokul Srinivasaragavan (UMD/Northwestern), Huei Sears (Rutgers), Anirudh Salgundi (UNC), report on behalf of a larger collaboration: We obtained further imaging of the optical counterpart to GRB 260705A (Saccardi et al., GCN 45079; Hamburg & Veres, GCN 45080) reported in Freeburn et al., GCN 45105. We observed with the Goodman High Throughput Spectrograph (GHTS) in imaging mode at a midpoint of UT 2026-07-11 10:15:00 corresponding to 5.88 days after the trigger and with the Gemini Multi-object Spectrograph (GMOS) mounted on Gemini south at UT 2026-07-08 09:08:46 corresponding to 2.83 days after the trigger. We obtain the following upper limits: | Instrument | MJD | Filter | Upper limit | | ---------- | --------- | ------ | ----------- | | GMOS | 61229.381 | r | 23.7 | | GHTS | 61232.423 | i | 23.0 | | GHTS | 61232.434 | r | 23.3 | We also obtained imaging and spectroscopic data using the GMOS-S instrument mounted on the Gemini South telescope. The acquisition images consisted of a sequence of 20 s and 30 s exposures in the r-band. We acquired 4 x 900 s spectroscopic observations using the B480 grating centered at 520 nm. Data were reduced using DRAGONS. The spectrum is host dominated and shows no prominent transient features. We identify several narrow absorption and emission features at a common redshift of z = 0.1840 +/- 0.0005. Motivated by the photometric and spectroscopic non-detections, we conducted more careful analysis of the images taken on the night of 2026-07-07, detailed in Freeburn et al., GCN 45105. Despite a convincing detection in the coadded image, we found that the source was not present when differencing the individual GMOS exposures. Similarly, in the SOAR data, the source was not reliably recovered when varying the subtraction parameters. We therefore conclude that the source is likely spurious. View this GCN Circular online at https://gcn.nasa.gov/circulars/45189. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43404] GRB 260714B: Insight-HXMT/HE detection
by GCN Circulars 19 Jul '26

19 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45188 SUBJECT: GRB 260714B: Insight-HXMT/HE detection DATE: 26/07/19 15:10:41 GMT FROM: Xinghao Luo at IHEP <2952704891(a)qq.com> Xing-Hao Luo, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2026-07-14T18:23:29.500 (T0), Insight-HXMT/HE detected the GRB 260714B, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #45158) AstroSat CZTI (U. Pathak et.al., GCN#45163), GECAM-B (Yang-Zhao Ren et.al., #45174) and SVOM/GRM (Yang-Zhao Ren et.al., GCN#45176). The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 10.88 +0.02/-0.04 s. The 1s peak rate, measured from T0+0.13 s, is 8893 cnts/sec. Insight-HXMT/HE detected a total of 36543 counts from this burst. The HXMT/HE light curve can be found here: https://www.bursthub.cn/gcn/2026/hxmtgrb260714B.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://hxmten.ihep.ac.cn/ View this GCN Circular online at https://gcn.nasa.gov/circulars/45188. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43403] GRB 260718A: EP-FXT follow-up observation
by GCN Circulars 19 Jul '26

19 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45187 SUBJECT: GRB 260718A: EP-FXT follow-up observation DATE: 26/07/19 02:45:20 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> A.Li (BNU), C. Y. Wang (THU), Y. Q. Zhao (USTC,PRIC), J. P. Chen (SYSU), W.Chen and H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of GRB 260718A detected by SVOM/ECLAIRs (Antier et al., GCN 45177), which also triggered Fermi-GBM (Holzmann Airasca et al., GCN 45181). The follow-up observation started at 2026-07-18T12:09:38 (UTC), about 53 min after the SVOM-ECLAIRs trigger, with a total exposure time of around 6.2 ks. An uncatalogued source was found within the ECLAIRs error circle. The position of the source is at R.A., Dec. = 37.3004, -56.1050 deg (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The average unabsorbed flux is 2.16(+0.62/-0.33) x 10^(-12) erg/s/cm^2 in the 0.5-10 keV energy band. 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/45187. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43402] Fermi trigger No 806104130: Global MASTER-Net observations report
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45186 SUBJECT: Fermi trigger No 806104130: Global MASTER-Net observations report DATE: 26/07/18 22:31:13 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB260718.91 (trigger No 806104130,00h 29m 02.40s , -00d 33m 00.0s, R=11.89) errorbox 792 sec after notice time and 803 sec after trigger time at 2026-07-18 22:02:09 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 72 deg. The sun altitude is -75.6 deg. The galactic latitude b = -63 deg., longitude l = 112 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3433519 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 834 | 2026-07-18 22:02:09 | MASTER-SAAO | (23h 54m 05.72s , -03d 01m 04.2s) | C | 60 | 15.0 | 1139 | 2026-07-18 22:07:14 | MASTER-SAAO | (00h 09m 13.60s , -01d 06m 25.9s) | C | 60 | 14.8 | 1244 | 2026-07-18 22:08:59 | MASTER-SAAO | (00h 09m 20.07s , -01d 07m 24.0s) | C | 60 | 14.8 | 1350 | 2026-07-18 22:10:46 | MASTER-SAAO | (00h 09m 13.69s , -01d 06m 25.2s) | C | 60 | 13.2 | 1459 | 2026-07-18 22:12:34 | MASTER-SAAO | (00h 09m 19.04s , -01d 07m 06.4s) | C | 60 | 15.4 | 1565 | 2026-07-18 22:14:20 | MASTER-SAAO | (00h 09m 12.41s , -01d 06m 25.3s) | C | 60 | 15.6 | 1666 | 2026-07-18 22:16:01 | MASTER-SAAO | (00h 24m 32.56s , -03d 01m 04.1s) | C | 60 | 12.2 | 2184 | 2026-07-18 22:24:39 | MASTER-SAAO | (00h 09m 13.55s , -03d 00m 26.1s) | C | 60 | 16.4 | 2282 | 2026-07-18 22:26:17 | MASTER-SAAO | (00h 09m 15.33s , -04d 55m 25.9s) | C | 60 | 17.1 | 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/45186. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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