GRB 260410B
GCN Circular 44288
Subject
GRB 260410B: Insight-HXMT/HE detection
Date
2026-04-13T13:29:15Z (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 2026-04-10T12:22:26.900 (T0), Insight-HXMT/HE detected GRB 260410B, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #44255) and SVOM/GRM (Chen-Wei Wang et al., GCN #44257).
The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 0.2 +/- 0.04 s. Insight-HXMT/HE detected a total of 1102 counts from this burst.
The Insight-HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb260410B.png
All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 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 44273
Subject
GRB 260410B: Fermi GBM Observation
Date
2026-04-12T05:02:47Z (11 days ago)
From
rhamburg@usra.edu
Via
Web form
R. Hamburg (USRA) and U. Pathak (IIT Bombay) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 12:22:26.93 UT on 10 April 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260410B (trigger 797516551/260410516), which was also detected by SVOM/GRM (Wang et al. 2026, GCN 44257).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 4.22, Dec = 37.74 (J2000 degrees, equivalent to J2000 0h 16m, +37d 44'), with a statistical uncertainty of 5.61 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 90 degrees.
The GBM light curve single bright emission episode with a duration (T90) of about 0.19 s (50-300 keV). The time-averaged spectrum from T0-0.04 to T0+0.16 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.01 +/- 0.09 and the cutoff energy, parameterized as Epeak, is 1220 +/- 30 keV.
The event fluence (10-1000 keV) in this time interval is (1.09 +/- 0.03)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 11.3 +/- 0.9 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 44257
Subject
GRB 260410B: SVOM/GRM detection of a short faint burst
Date
2026-04-10T15:59:54Z (12 days ago)
Edited On
2026-04-10T18:24:26Z (12 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
Chen-Wei Wang (IHEP), F. Piron (LUPM) and C. Lachaud (APC) report on behalf of the SVOM mission team:
At 2026-04-10T12:22:27 UTC (T0), SVOM/GRM triggered on the gamma-ray burst GRB 260410B (SVOM burst-id sb26041001) on a timescale of 1 seconds and with a signal-to-noise ratio (SNR) of 5.90.
This transient was also detected by Fermi/GBM (GCN Circulars #44255).
At the time of this burst, SVOM/ECLAIRs was not taking data.
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that the short burst GRB 260410B consists a single pulse with T90 of 0.20 +0.12/-0.06 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb260410B.png
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE.
The Burst Advocate (BA) on shift for this alert is Chenwei Wang: cwwang AT ihep.ac.cn.
Please contact the BA by email if you require additional information.
GCN Circular 44255
Subject
GRB 260410B: Fermi GBM Final Real-time Localization
Date
2026-04-10T15:01:29Z (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 12:22:26 UT on 10 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260410B (trigger 797516551.925452 / 260410516).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 4.2, Dec = 37.7 (J2000 degrees, equivalent to J2000 00h 16m, 37d 42'), with a statistical uncertainty of 5.6 degrees.
The angle from the Fermi LAT boresight is 90.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260410516/quicklook/glg_skymap_all_bn260410516.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/bn260410516/quicklook/glg_healpix_all_bn260410516.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260410516/quicklook/glg_lc_medres34_bn260410516.gif