GRB 261005A
GCN Circular 45820
Subject
GRB 261005A: Glowbug gamma-ray detection
Date
2026-10-06T16:10:45Z (13 hours 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 261005A, which was also detected by Fermi/GBM (GCN 45811).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-10-05 20:19:00.664 with a duration of 5.1 s and a total significance of about 13.5 sigma. The light curve comprises a single peak.
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.
[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 45811
Subject
GRB 261005A: Fermi GBM Final Real-time Localization
Date
2026-10-05T20:29:41Z (a day 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 20:19:03 UT on 5 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261005A (trigger 812924348.321234 / 261005847).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 339.9, Dec = 5.5 (J2000 degrees, equivalent to J2000 22h 39m, 5d 30'), with a statistical uncertainty of 5.8 degrees.
The angle from the Fermi LAT boresight is 64.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261005847/quicklook/glg_skymap_all_bn261005847.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/bn261005847/quicklook/glg_healpix_all_bn261005847.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261005847/quicklook/glg_lc_medres34_bn261005847.gif