GRB 260805B
GCN Circular 45291
Subject
GRB 260805B: Glowbug gamma-ray detection
Date
2026-08-05T19:41:57Z (19 days ago)
From
C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>
Via
Web form
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.
GCN Circular 45289
Subject
GRB 260805B: Fermi GBM Final Localization
Date
2026-08-05T15:19:19Z (20 days ago)
From
Marianna Dafčíková at Masaryk University <500025@mail.muni.cz>
Via
Web form
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/quicklook/glg_skymap_all_bn260805484.png
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/quicklook/glg_healpix_all_bn260805484.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260805484/quicklook/glg_lc_medres34_bn260805484.gif"
GCN Circular 45287
Subject
GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
Date
2026-08-05T12:19:46Z (20 days ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
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