GRB 260917A
GCN Circular 45613
Subject
GRB 260917A: Glowbug gamma-ray detection
Date
2026-09-17T15:22:35Z (4 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, confirms the detection of GRB 260917A, which was detected by Fermi/GBM (GCN 45603, 45604).
The burst onset is at 2026-09-17 02:24:07.4 with a burst duration of ~8.5 s. The detection occurred during a time of high background as Glowbug was in the southern radiation belt. The lightcurve comprises a single peak corresponding to the first, brightest peak observed in the Fermi/GBM lightcurve.
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 45604
Subject
GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
Date
2026-09-17T02:57:11Z (5 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
811304653 at 02:24:08 on 17 Sept. 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) = 310.2 deg
Decl.(2000.0) = -31.9 deg
The 1 sigma statistical error radius is 1.4 deg.
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB260917100/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB260917100/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB260917100/json
GCN Circular 45603
Subject
GRB 260917A: Fermi GBM Final Real-time Localization
Date
2026-09-17T02:34:35Z (5 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 02:24:08 UT on 17 Sep 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260917A (trigger 811304653.400746 / 260917100).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 311.6, Dec = -32.8 (J2000 degrees, equivalent to J2000 20h 46m, -32d 47'), with a statistical uncertainty of 1.7 degrees.
The angle from the Fermi LAT boresight is 121.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260917100/quicklook/glg_skymap_all_bn260917100.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/bn260917100/quicklook/glg_healpix_all_bn260917100.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260917100/quicklook/glg_lc_medres34_bn260917100.gif