GRB 260617A
GCN Circular 45033
Subject
GRB 260617A: Glowbug gamma-ray detection of a short burst
Date
2026-06-23T22:12:11Z (11 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 260617A, which was also detected by Fermi/GBM (GCN 44969, 44972), Konus-Wind and Mars-Odyssey/HEND (GCN 44982, 44998), and CALET (GCN 44989).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-06-17 21:36:42.640 with a duration of 0.26 s and a total significance of about 27 sigma. The light curve comprises a multi-peaked emission similar to the CALET light curve (GCN 44989).
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 44998
Subject
Konus-Wind detection of GRB 260617A
Date
2026-06-19T12:29:15Z (16 days ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short-duration GRB 260617A
(Fermi-GBM detection: Fermi GBM team, GCN 44969;
Godwin & Meegan, GCN 44972;
IPN triangulation: Kozyrev et al., GCN 44982;
CALET-GBM detection: Torii et al., GCN 44989)
triggered Konus-Wind at T0=77808.934 s UT (21:36:48.934).
The burst light curve shows a multi-peaked pulse,
which starts at ~T0-64 ms and has a total duration of ~150 ms.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB260617_T77808/
As observed by Konus-Wind, the burst
had the total fluence of 1.28(-0.16,+0.19)x10^-6 erg/cm2,
and the 16-ms peak flux, measured from T0-0.060 s,
of 1.73(-0.36,+0.38)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
Since the brightest peak of the burst light curve
was detected before the trigger, the spectral analysis
was performed using the KW 3-channel light curve data.
Modelling the KW 3-channel time-integrated spectrum
(measured from T0-0.064 s to T0+0.084 s)
by a power law with exponential cutoff (CPL) model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep),
yields alpha = -0.26(-0.32,+0.40) and Ep = 537(-85,+129) keV.
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.
GCN Circular 44989
Subject
GRB 260617A: CALET Gamma-Ray Burst Monitor detection
Date
2026-06-19T08:20:00Z (16 days ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
S. Torii (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), Y. Akaike,
K. Kobayashi (Waseda U), Y. Shimizu, 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 260617A
at 21:36:43.92 UTC on 17 June 2026 (trigger #1465767277;
https://cgbm.calet.jp/cgbm_trigger/flight/1465767277/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 Fermi GBM (The Fermi GBM team et al., GCN #44969;
Godwin et al., GCN #44972), Konus-Wind and Mars-Odyssey (IPN triangulation: Kozyrev et al., GCN #44982).
The burst signal was seen by HXM1 and SGM. The burst light curve shows a short pulse from T-0.25 s to T-0.15 s.
The T90 and T50 durations measured with the SGM data are 0.09 +/- 0.02 s
and 0.05 +/- 0.01 s in the 40-1000 keV band, respectively.
The ground-processed light curve is available at:
https://cgbm.calet.jp/cgbm_trigger/ground/1465767277/
The CALET data used in this analysis were provided by
the Waseda CALET Operation Center located at Waseda University.
GCN Circular 44982
Subject
IPN triangulation of GRB 260617A (short)
Date
2026-06-18T21:50:23Z (16 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, 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 260617A
(Fermi-GBM detection: Fermi GBM team, GCN 44969;
Godwin & Meegan, GCN 44972)
was detected by Fermi (GBM trigger 803425008), Konus-Wind,
and Mars-Odyssey (HEND) at about 77803 s UT (21:36:43).
We have triangulated it to the 3 sigma localization region
whose area is 3360 sq. arcmin, and its maximum
dimension is 4.4 deg (the minimum one is 12.9 arcmin).
A triangulation map and HEALPix FITS files are posted at
http://www.ioffe.ru/LEA/GRBs/GRB260617_T77808/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 44972
Subject
GRB 260617A: Fermi GBM Detection
Date
2026-06-18T05:18:48Z (17 days ago)
From
Matt Godwin <msg0028@uah.edu>
Via
Web form
Matt Godwin (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 21:36:43.68 UT on 17 June 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260617A (trigger 803425008/260617900).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 224.34, Dec = -12.61 (J2000 degrees, equivalent to
J2000 15h 47m, -16d 43'), with a statistical uncertainty of 7.08 degrees.
(radius, 1-sigma containment, statistical only; there is additionally a
systematic error which we have characterized as a mixture of two Gaussians,
one with a radius of 1.8 degrees (52% contribution) and one with a radius
of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]).
The angle from the Fermi LAT boresight is 99 degrees.
The GBM light curve consists of a short, bright burst with a duration (T90)
of about 0.14 s (50-300 keV). The time-averaged spectrum
from T0-0.08 to T0+0.259 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.56 +/- 0.04 and the cutoff energy,
parameterized as Epeak, is 700 +/- 40 keV.
The event fluence (10-1000 keV) in this time interval is
(7.4 +/- 0.5)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band is 21 +/- 1 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 44970
Subject
GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
Date
2026-06-17T21:51:34Z (17 days ago)
Edited On
2026-06-18T17:14:46Z (17 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov>
Via
email
GCN Circular 44969
Subject
GRB 260617A: Fermi GBM Final Real-time Localization
Date
2026-06-17T21:49:10Z (17 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 SHORT GRB
At 21:36:43 UT on 17 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260617A (trigger 803425008.678884 / 260617900).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 236.9, Dec = -16.7 (J2000 degrees, equivalent to J2000 15h 47m, -16d 41'), with a statistical uncertainty of 12.7 degrees.
The angle from the Fermi LAT boresight is 100.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260617900/quicklook/glg_skymap_all_bn260617900.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/bn260617900/quicklook/glg_healpix_all_bn260617900.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260617900/quicklook/glg_lc_medres34_bn260617900.gif