GRB 260410A
GCN Circular 44290
Subject
GRB 260410A: Glowbug gamma-ray detection of a short burst
Date
2026-04-13T21:49:59Z (9 days ago)
Edited On
2026-04-14T14:41:16Z (9 days ago)
From
C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of 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 260410A, which was detected by Fermi/GBM (GCN 44252, 44258), Fermi/LAT (GCN 44253), CALET (GCN 44283), Konus-Wind (GCN 44286), and Insight-HXMT/HE (GCN 44287).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-04-10 07:03:55.848 with a duration of 0.38 s and a total significance of about 46 sigma. The light curve comprises an initial faint peak with a duration of ~25-ms, followed by a bright double-peaked structure with maxima at ~T0+0.13s and ~T0+0.24s.
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 44287
Subject
GRB 260410A: Insight-HXMT/HE detection
Date
2026-04-13T12:54:41Z (10 days ago)
From
zhangjinpeng@ihep.ac.cn
Via
Web form
Jin-Peng Zhang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:
At 2026-04-10T07:03:56.950 (T0), Insight-HXMT/HE detected GRB 260410A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #44252; Hamburg et al., GCN #44258) and Fermi/LAT (Holzmann Airasca et al., GCN #44253).
The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 0.6 +0.5/-0.3 s. Insight-HXMT/HE detected a total of 1462 counts from this burst.
The Insight-HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb260410A.png
All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the low gain mode with the energy range of about 300-3000 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope.
Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://hxmten.ihep.ac.cn
GCN Circular 44286
Subject
Konus-Wind detection of GRB 260410A (short/hard)
Date
2026-04-13T11:52:18Z (10 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 260410A
(Fermi-GBM detection: Fermi GBM team, GCN Circ. 44252,
Hamburg et al., GCN Circ. 44258;
Fermi-LAT detection: Holzmann Airasca et al., GCN Circ. 44253;
CALET-GBM detection: Ricciarini et al., GCN Circ. 44283)
triggered Konus-Wind at T0=25436.09 s UT (07:03:56.090).
The burst light curve shows a multipeaked structure,
which starts at ~T0-0.1 s and has a total duration of ~0.3 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB260410_T25436/
As observed by Konus-Wind, the burst
had a fluence of 3.36(-0.54,+0.53)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.054 s,
of 2.53(-0.69,+0.68)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+0.192 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.06(-0.34,+0.62),
the high energy photon index beta = -2.06(-0.51,+0.28),
the peak energy Ep = 784(-283,+341) keV
(chi2 = 21/27 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.
GCN Circular 44283
Subject
GRB 260410A: CALET Gamma-Ray Burst Monitor detection
Date
2026-04-13T08:51:45Z (10 days ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto, S. Sugita,
Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu,
T. Tamura (Kanagawa U), N. Cannady (GSFC), M. L. Cherry (LSU),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The CALET Gamma-ray Burst Monitor (CGBM) detected GRB 260410A
(Fermi GBM Final Real-time Localization: Fermi GBM team, GCN #44252;
Fermi-LAT detection: Holzmann Airasca et al., GCN #44253; Fermi GBM
Observation: Hamburg et al., GCN #44258) at 07:03:56.88 UTC on 10 April 2026
(https://cgbm.calet.jp/cgbm_trigger/flight/1459839839/index.html).
The burst signal was seen by all CGBM detectors.
The burst light curve shows a short pulse starting
at T+0.06 s, peaking at T+0.18 s, and ending at T+0.29 s.
The T90 and T50 durations measured with the SGM data are 0.21 +/- 0.04 s
and 0.10 +/- 0.03 s (40-1000 keV), respectively.
The ground-processed light curve is available at
https://cgbm.calet.jp/cgbm_trigger/ground/1459839839/
The CALET data used in this analysis were provided by
the Waseda CALET Operation Center located at Waseda University.
GCN Circular 44260
Subject
GRB 260410A: COLIBRÍ optical upper limit
Date
2026-04-11T06:40:10Z (12 days ago)
From
a.kuwata@irya.unam.mx
Via
Web form
Asuka Kuwata (UNAM), Damien Dornic (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report:
We imaged the field of the Fermi GRB 260410A (A. Holzmann Airasca et al., GCN Circ. 44253) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-04-11 03:50:46 to 04:47:10 UTC (from 20.7805 to 21.7371 hours after the trigger) and obtained 2460 seconds of simultaneous exposure in the r/z filters.
The data were reduced, coadded, calibrated, and analyzed with the COLIBRÍ ASU pipeline.
The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction.
In the stacked image, we do not detect any new source at the Fermi-LAT source position (A. Holzmann Airasca et al., GCN Circ. 44253) down to the following 5-sigma limit:
r > 23.26
z > 21.83
We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular 44258
Subject
GRB 260410A: Fermi GBM Observation
Date
2026-04-10T17:00:13Z (13 days ago)
Edited On
2026-04-10T21:12:09Z (12 days ago)
From
rhamburg@usra.edu
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of rhamburg@usra.edu
Via
Web form
R. Hamburg (USRA), U. Pathak (IIT Bombay) and R. Sonawane (IISER TVM) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 07:03:57.00 UT on 10 April 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260410A (trigger 797497441/260410294), which was also detected by Fermi-LAT (Holzmann Airasca et al. 2026, GCN 44253). The Fermi GBM real-time localization (GCN 44252) is consistent with the Fermi-LAT position.
The angle from the Fermi LAT boresight is 49 degrees.
The GBM light curve consists of a single bright emission episode with a duration (T90) of about 1 s (50-300 keV). The time-averaged spectrum from T0-0.07 to T0+0.30 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.17 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 960 +/- 30 keV.
The event fluence (10-1000 keV) in this time interval is (1.33 +/- 0.01)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.0 s in the 10-1000 keV band is 12.0 +/- 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 44253
Subject
GRB 260410A: Fermi-LAT detection
Date
2026-04-10T14:03:21Z (13 days ago)
From
A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca@unitn.it>
Via
Web form
A. Holzmann Airasca (Univ. Trento and INFN Bari), D. Depalo (Politecnico and INFN Bari), S. Lopez (CNRS / IN2P3), R. Gupta (NASA / GSFC) and F. Longo (Univ. and INFN Trieste) report on behalf of the Fermi-LAT team the detection of a likely SHORT GRB:
At 07:03:57.00 UT on April 10th, 2026, Fermi-LAT detected high-energy emission from GRB 260410A, which was also detected by Fermi-GBM (trigger 797497442 / 260410294, GCN #44252).
The best LAT on-ground location is found to be
RA, Dec = 110.67, -20.94 (J2000)
with an error radius of 0.17 deg (90 % containment, statistical error only).
This was 49 deg from the LAT boresight at the time of the trigger.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance.
The photon flux above 100 MeV in the time interval 0 - 2 s after the GBM trigger is (1.23 ± 0.38)E-3 ph/cm2/s. The estimated photon index above 100 MeV is -1.84 ± 0.24. The highest-energy photon is a 6.1 GeV event, which is observed 0.37 seconds after the GBM trigger.
The Fermi-LAT point of contact for this burst is Sara Cutini (sara.cutini@pg.infn.it).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
GCN Circular 44252
Subject
GRB 260410A: Fermi GBM Final Real-time Localization
Date
2026-04-10T07:14:31Z (13 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 07:03:56 UT on 10 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260410A (trigger 797497441.997288 / 260410294).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 108.3, Dec = -28.9 (J2000 degrees, equivalent to J2000 07h 13m, -28d 53'), with a statistical uncertainty of 8.2 degrees.
The angle from the Fermi LAT boresight is 41.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260410294/quicklook/glg_skymap_all_bn260410294.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/bn260410294/quicklook/glg_healpix_all_bn260410294.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260410294/quicklook/glg_lc_medres34_bn260410294.gif