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

[vsnet-grb-info 43509] GRB 260805C: Glowbug gamma-ray detection
by GCN Circulars 05 Aug '26

05 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45292 SUBJECT: GRB 260805C: Glowbug gamma-ray detection DATE: 26/08/05 21:24:48 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 260805C. Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-08-05 07:27:39.496 with a duration of ~12 s and a total significance of about 36 sigma. The light curve comprises a single FRED-shaped pulse. Additional lower-level emission up to ~T0+22s may be present in the Glowbug light curve at low significance. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/45292. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43508] GRB 260805B: Glowbug gamma-ray detection
by GCN Circulars 05 Aug '26

05 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45291 SUBJECT: GRB 260805B: Glowbug gamma-ray detection DATE: 26/08/05 19:41:57 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 260805B, which was also detected by Fermi/GBM (GCN 45287, 45289). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-08-05 11:36:49.640 with a duration of 14.6 s and a total significance of about 20.3 sigma. The light curve comprises a broad emission profile similar to that observed by Fermi/GBM. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/45291. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43507] Fermi GRB 260805A: Global MASTER-Net observations report
by GCN Circulars 05 Aug '26

05 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45290 SUBJECT: Fermi GRB 260805A: Global MASTER-Net observations report DATE: 26/08/05 18:16:07 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 GRB 260805A ( Fermi GBM team, GCN 45286) errorbox 26848 sec after notice time and 26944 sec after trigger time at 2026-08-05 16:47:37 UT, with upper limit up to 18.3 mag. Observations started at twilight. The observations began at zenith distance = 73 deg. The sun altitude is -10.3 deg. The galactic latitude b = 38 deg., longitude l = 61 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3458691 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 26974 | 2026-08-05 16:47:37 | MASTER-SAAO | (16h 46m 23.79s , +37d 05m 59.0s) | C | 60 | 16.2 | 27079 | 2026-08-05 16:49:21 | MASTER-SAAO | (16h 46m 20.13s , +37d 05m 05.7s) | C | 60 | 16.5 | 27177 | 2026-08-05 16:51:00 | MASTER-SAAO | (16h 53m 24.94s , +39d 00m 48.3s) | C | 60 | 16.7 | 27274 | 2026-08-05 16:52:37 | MASTER-SAAO | (16h 33m 55.61s , +39d 00m 11.2s) | C | 60 | 17.1 | 27371 | 2026-08-05 16:54:13 | MASTER-SAAO | (16h 40m 42.58s , +35d 13m 18.4s) | C | 60 | 17.3 | 27468 | 2026-08-05 16:55:51 | MASTER-SAAO | (16h 42m 02.63s , +40d 54m 37.3s) | C | 60 | 17.1 | 27565 | 2026-08-05 16:57:28 | MASTER-SAAO | (16h 59m 16.29s , +35d 12m 25.7s) | C | 60 | 17.4 | 27662 | 2026-08-05 16:59:05 | MASTER-SAAO | (16h 27m 13.66s , +37d 07m 26.1s) | C | 60 | 17.8 | 27763 | 2026-08-05 17:00:46 | MASTER-SAAO | (17h 02m 11.79s , +40d 53m 02.6s) | C | 60 | 17.5 | 27865 | 2026-08-05 17:02:28 | MASTER-SAAO | (16h 54m 27.27s , +33d 17m 55.3s) | C | 60 | 17.9 | 27965 | 2026-08-05 17:04:07 | MASTER-SAAO | (17h 05m 29.88s , +37d 04m 27.6s) | C | 60 | 17.8 | 28066 | 2026-08-05 17:05:49 | MASTER-SAAO | (16h 36m 16.59s , +33d 18m 58.1s) | C | 60 | 18.2 | 28172 | 2026-08-05 17:07:35 | MASTER-SAAO | (16h 21m 54.26s , +40d 56m 57.8s) | C | 60 | 18.2 | 28273 | 2026-08-05 17:09:16 | MASTER-SAAO | (16h 22m 01.69s , +35d 14m 54.4s) | C | 60 | 18.3 | 28369 | 2026-08-05 17:10:52 | MASTER-SAAO | (16h 22m 02.96s , +35d 12m 55.3s) | C | 60 | 18.3 | 28476 | 2026-08-05 17:12:39 | MASTER-SAAO | (16h 51m 41.89s , +42d 49m 29.3s) | C | 60 | 17.9 | 28576 | 2026-08-05 17:14:19 | MASTER-SAAO | (17h 13m 05.13s , +39d 00m 07.2s) | C | 60 | 18.3 | 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/45290. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43506] GRB 260805B: Fermi GBM Final Localization
by GCN Circulars 05 Aug '26

05 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45289 SUBJECT: GRB 260805B: Fermi GBM Final Localization DATE: 26/08/05 15:19:19 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> The Fermi GBM team reports the detection of a likely LONG GRB "At 11:36:52.81 UT on 05 August 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260805B (trigger 807622617/260805484). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 259.42, Dec = 64.59 (J2000 degrees, equivalent to J2000 17h 17m, +64d 35'), with a statistical uncertainty of 2.15 degrees. The angle from the Fermi LAT boresight is 31 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260805484/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260805484/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260805484/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/45289. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43505] GRB 260804A: Glowbug gamma-ray detection
by GCN Circulars 05 Aug '26

05 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45288 SUBJECT: GRB 260804A: Glowbug gamma-ray detection DATE: 26/08/05 13:56:11 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 260804A, which was also detected by Fermi/GBM (GCN 45281). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-08-04 03:07:09.160 with a duration of 19.7 s and a total significance of about 23.6 sigma. The light curve comprises a faint peak at ~T0, multi-peaked emission from ~T0+11s to +16s, and the brightest peak at ~T0+18s. Note that data from ~T0+8s to +12s suffered from deadtime in various detectors. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/45288. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43504] GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
by GCN Circulars 05 Aug '26

05 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45287 SUBJECT: GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484) DATE: 26/08/05 12:19:46 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 807622617 at 11:36:52 on 05 Aug. 2026 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) = 255.8 deg Decl.(2000.0) = 67.9 deg The 1 sigma statistical error radius is 2.9 deg. We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB260805484/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB260805484/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB260805484/json View this GCN Circular online at https://gcn.nasa.gov/circulars/45287. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43503] GRB 260805A: Fermi GBM Final Localization
by GCN Circulars 05 Aug '26

05 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45286 SUBJECT: GRB 260805A: Fermi GBM Final Localization DATE: 26/08/05 11:02:33 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> The Fermi GBM team reports the detection of a likely LONG GRB "At 09:18:33.28 UT on 05 August 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260805A (trigger 807614318/260805388). This trigger was initially classified as Distant Particles by the flight software, but is in fact a GRB. The on-ground calculated location, using the Fermi GBM trigger data, is RA = 252.53, Dec = 34.93 (J2000 degrees, equivalent to J2000 16h 50m, +34d 56'), with a statistical uncertainty of 3.11 degrees. The angle from the Fermi LAT boresight is 112 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260805388/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260805388/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260805388/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/45286. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43502] AT 2026wki: EP/FXT follow-up observations
by GCN Circulars 04 Aug '26

04 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45285 SUBJECT: AT 2026wki: EP/FXT follow-up observations DATE: 26/08/04 12:56:36 GMT FROM: Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi(a)ynao.ac.cn> R.-Z. Li (YNAO, CAS), J. Mao (YNAO, CAS), M. Pillas (IAP), S. Antier (IJCLAB), D. Akl (NYUAD) report on behalf of a larger collaboration: We report one EP/FXT Target of Opportunity (ToO) observation of the optical transient AT 2026wki. The EP/FXT follow-up observation started at 2026-08-01T21:06:21 (UTC), approximately 3.64 days after the first detection of the transient, with a total exposure time of 4.8 ks. No X-ray source was detected at the position of AT 2026wki within the 10 arcsec error radius (90% C.L. statistical and systematic). The estimated flux upper limit is 5.59 x 10^-14 erg/cm^2/s in the 0.5-10 keV band (90% C.L.). View this GCN Circular online at https://gcn.nasa.gov/circulars/45285. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43501] GRB 260730B: CALET Gamma-Ray Burst Monitor detection
by GCN Circulars 04 Aug '26

04 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45284 SUBJECT: GRB 260730B: CALET Gamma-Ray Burst Monitor detection DATE: 26/08/04 09:55:59 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> Y. Shimizu (Kanagawa U), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), T. Tamura (Kanagawa U), N. Cannady (GSFC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: The CALET Gamma-ray Burst Monitor (CGBM) detected GRB 260730B at 13:13:50.13 UTC on 30 July 2026 (trigger #1469452426; https://cgbm.calet.jp/cgbm_trigger/flight/1469452426/index.html) No real-time CGBM GCN notice was distributed about this trigger because the real-time communication from the ISS was off (loss of signal). This event was also reported by NuSTAR (Waratkar et al., GCN #45262) and AstroSat CZTI (Goyal et al., GCN #45265). The burst signal was seen by all CGBM detectors. The burst light curve shows a multi-peaked structure starting at T-5.5 s, peaking at T+5.9 s, and ending at T+22.1 s. The T90 and T50 durations measured with the SGM data are 17.1 +/- 0.9 s and 6.1 +/- 0.9 s in the 40-1000 keV band, respectively. The ground-processed light curve is available at: https://cgbm.calet.jp/cgbm_trigger/ground/1469452426/ The CALET data used in this analysis were provided by the Waseda CALET Operation Center located at Waseda University. View this GCN Circular online at https://gcn.nasa.gov/circulars/45284. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43500] GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
by GCN Circulars 04 Aug '26

04 Aug '26

TITLE: GCN CIRCULAR NUMBER: 45283 SUBJECT: GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova DATE: 26/08/04 08:19:29 GMT FROM: Gregory Corcoran at University College Dublin <gregory.corcoran(a)ucdconnect.ie> G. Corcoran (UCD), A. Martin-Carrillo (UCD), D. B. Malesani (DAWN/NBI and Radboud), L. P. Xin (NAOC) report on behalf of the Stargate collaboration: We observed the counterpart of GRB 260708A detected by Fermi-GBM, Fermi-LAT, Glowbug and GECAM (Fermi-GBM Team, GCN 45115; Holzmann Airasca et al., GCN 45117; Malacaria, GCN 45124; Ren et al., GCN 45126; Cheung et al., GCN 45130), AT 2026stf (Shilova et al., GCN 45123; Freeberg et al., GCN 45127; Shi et al., GCN 45140, Sheng et al., GCN 45147; Li et al., GCN 45150) with a possible emerging supernova (Shi et al., GCN 45280) using the FORS2 spectrograph with the 300V grism and the GG435 order blocker on the ESO VLT UT1 (Antu). Observations started at 23:13:36 UT on 2026-08-02 (~25.5 days after the GRB trigger). Our spectra cover the wavelength range ~4560-8690 AA and consist of 4 exposures of 600 s each. In an R-band acquisition image we measure a magnitude of R=19.12+/-0.09 (AB) calibrated using nearby stars in the SkyMapper catalog and not corrected for Galactic extinction. We note that this is likely contaminated with host light as the candidate host has an r-band magnitude of r=20.06+/-0.02 from the DECam Local Volume Exploration Survey (DELVE, Drlica-Wagner et al. 2021, doi:10.3847/1538-4365/ac079d). In a stack of the quicklook spectra provided on the ESO archive, we identify clear narrow emission features from the candidate host galaxy consistent with a redshift of z = 0.055. In addition, using SNID-SAGE (Stoppa et al. 2026, doi:10.1093/mnras/stag1066) we identify clear supernova features consistent with a broad-lined type Ic (Ic-BL) supernova post peak at a consistent redshift. A comparison figure of our spectrum (blue line) to a template Ic-BL SN is available at the following link: https://shorturl.at/rzxgB We acknowledge the excellent support from the observing staff in Paranal, in particular Elisa Rita Garro and Edouard Gonzalez. View this GCN Circular online at https://gcn.nasa.gov/circulars/45283. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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