GRB 260916B
GCN Circular 45636
Subject
Konus-Wind detection of GRB 260916B (short/hard)
Date
2026-09-18T16:14:18Z (3 days ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
email
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short GRB 260916B (Fermi-GBM detection: Fermi GBM team, GCN 45614; Trigg, GCN 45616;
IPN triangulation: Kozyrev et al., GCN 45630;
Glowbug detection: Cheung et al., GCN 45663)
triggered Konus-Wind (KW) at T0=54667.877 s UT (15:11:07.877).
The burst light curve shows a single pulse,
which starts at ~T0-0.1 s and has a duration of ~0.17 s.
The emission is seen up to ~700 keV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB260916_T54667/
As observed by Konus-Wind, the burst had the total fluence
of (8.82 ± 1.26)x10^-7 erg/cm^2 and a 16-ms peak energy flux,
measured from T0, of (1.30 ± 0.19)x10^-5 erg/cm^2/s
(both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+0.064 s)
is best fitted in the 20 keV - 15 MeV range by a power law with exponential
cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.00 (-0.33, + 0.38) and Ep = 330(-42,+59) keV, PGstat = 38/50 dof.
Fitting this spectrum by a Band GRB function yields the same values
of alpha and Ep, and only an upper limit on the high energy photon
index beta of -3.3
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.
GCN Circular 45633
Subject
GRB 260916B: Glowbug gamma-ray detection of a short burst
Date
2026-09-18T14:13:27Z (3 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 the short GRB 260916B, which was detected by Fermi/GBM (GCN 45614, 45616), Konus-Wind,
and Mars-Odyssey (HEND), resulting in an IPN localization (GCN 45630).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-09-16 15:11:03.312 with a duration of 0.16 s and a total significance of about 31.5 sigma. The lightcurve 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. 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 45630
Subject
IPN triangulation of GRB 260916B (short)
Date
2026-09-18T13:48:49Z (3 days ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
A. Ridnaia, D. Frederiks, A. Lysenko, V. Panteleeva, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi-GBM team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The short-duration GRB 260916B
(Fermi-GBM detection: Fermi GBM team, GCN 45614; Trigg, GCN 45616)
was detected by Fermi (GBM trigger 811264269), Konus-Wind,
and Mars-Odyssey (HEND) at about 54664 s UT (15:11:04).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
346.866 (23h 07m 28s) -32.509 (-32d 30' 34")
Corners:
346.902 (23h 07m 36s) -32.326 (-32d 19' 32")
346.911 (23h 07m 39s) -32.713 (-32d 42' 46")
346.829 (23h 07m 19s) -32.693 (-32d 41' 34")
346.820 (23h 07m 17s) -32.305 (-32d 18' 19")
---------------------------------------------
The error box area is 96 sq. arcmin, and its maximum
dimension is 25 arcmin (the minimum one is 4 arcmin).
The Sun distance was 149 deg.
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
https://www.ioffe.ru/LEA/GRBs/GRB260916_T54667/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 45616
Subject
GRB 260916B: Fermi GBM Detection
Date
2026-09-17T18:52:29Z (4 days ago)
From
atrigg2@lsu.edu
Via
Web form
A. C. Trigg (NPP ORAU, NASA MSFC) reports report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 15:11:04.34 UT on 16 September 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located
GRB 260916B (trigger 811264269/260916633).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 352.6, Dec = -35.7
(J2000 degrees, equivalent to J2000 23h 27m, -35d 55'), with a statistical uncertainty of 4.6 degrees.
(radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have
characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail
suffering a larger than 10 deg systematic error [Connaughton et al. 2015, ApJS, 216, 32]).
The angle from the Fermi LAT boresight is 110 degrees.
The GBM light curve consistent with a short single emission episode with a duration (T90) of about 0.1
s (50-300 keV). The time-averaged spectrum from T0-0.07 to T0+0.23 s is best fit by a power law
function with an exponential high-energy cutoff. The power law index is 0.24 +/- 0.01 and the cutoff
energy, parameterized as Epeak, is 980 +/- 30 keV.
The event fluence (10-1000 keV) in this time interval is (1.06 +/- 0.07)E-06 erg/cm^2. The 64-ms peak
photon flux measured starting from T0+0.00 s in the 10-1000 keV band is 13.4 +/- 1.0 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the
GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular 45614
Subject
GRB 260916B: Fermi GBM Final Localization
Date
2026-09-17T17:03:03Z (4 days ago)
From
atrigg2@lsu.edu
Via
Web form
The Fermi GBM team reports the detection of a likely SHORT GRB.
"At 15:11:04.34 UT on 16 September 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260916B (trigger 811264269/260916633).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 352.6, Dec = -35.7 (J2000 degrees, equivalent to J2000 23h 27m, -35d 55'), with a statistical uncertainty of 4.6 degrees.
The angle from the Fermi LAT boresight is 107 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260916633/quicklook/glg_skymap_all_bn260916633.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/bn260916633/quicklook/glg_healpix_all_bn260916633.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260916633/quicklook/glg_lc_medres34_bn260916633.gif"