GRB 260810A
GCN Circular 45402
Subject
GRB 260810A: SVOM/GRM observation
Date
2026-08-19T15:26:19Z (6 days ago)
From
guohx@ihep.ac.cn
Via
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SVOM/GRM team: Hao-Xuan Guo, Yue Wang, Chen-Wei Wang, Chao Zheng, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Oliver Godet (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered on-ground by GRB 260810A at 2026-08-10T19:09:43.050 UTC (T0), which is also detected by AstroSat CZTI (Arya et al., GCN #45363), Glowbug (Cheung et al., GCN #45365) and Insight-HXMT/HE (Yu et al. GCN #45392).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a pulse with a T90 of 18.0 +5.5/-2.5 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn/gcn/2026/svgrb260810A.png
In addition, the position of this burst, as determined by SVOM/GRM (RA = 234.55 deg, Dec = 2.02 deg, Err = 1.64 deg, 90% C. L., statistical only), is located at about 105 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. But the burst emission has been detected by ECLAIRs through reflection onto the Earth atmosphere, and GRM may also detected through atmosphere reflection.
With this localization, the time-averaged spectrum from T0-0.55 to T0+20.95 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.60 +/-0.03 and the cutoff energy, parameterized as Epeak, is 974 +281/-193 keV. The event fluence (10-1000 keV) in this time interval is (4.84 +0.07/-0.06)E-05 erg/cm^2.
The 1s peak spectrum, measured from T0+0.45 to T0+1.45 s, if fitted by a power law function with an exponential high-energy cutoff, the power law index is -1.04 +0.08/-0.07 and the cutoff energy, parameterized as Epeak, is 835 +152/-115 keV. The flux (10-1000 keV) in this time interval is (9.99 +0.21/-0.22)E-06 erg/cm^2/s.
The localization of GRB 260810A in the 'Amati' relation diagram is shown at:
https://www.bursthub.cn/gcn/2026/svgrb260810A_amati.png
The localization of GRB 260810A in the 'Yonetoku' relation diagram is shown at:
https://www.bursthub.cn/gcn/2026/svgrb260810A_yonetoku.png
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Hao-Xuan Guo (IHEP)(guohx@ihep.ac.cn)
GCN Circular 45392
Subject
GRB 260810A: Insight-HXMT/HE detection
Date
2026-08-18T06:57:05Z (7 days ago)
From
yzh807926@163.com
Via
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Zheng-Hang Yu, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:
At 2026-08-10T19:09:43.350 (T0), Insight-HXMT/HE detected GRB 260810A, which is also detected by AstroSat CZTI (A. Arya et al., GCN #45363), and Glowbug (C.C. Cheung et al., GCN #45365)
The Insight-HXMT/HE light curve mainly consists of two pulses with a T90 of 18.0 +7.0/-5.5 s. The 1 s peak rate, measured from T0+0.25 s, is 4028 cnts/sec. Insight-HXMT/HE detected a total of 15728 counts from this burst.
The Insight-HXMT/HE light curve can be found here:
https://www.bursthub.cn/gcn/2026/hxmtgrb260810A.png
All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the Normal 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 45365
Subject
GRB 260810A: Glowbug gamma-ray detection
Date
2026-08-12T19:05:46Z (12 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 260810A, which was also detected by AstroSat (GCN 45363).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-08-10 19:09:41.760 with a duration of 19.5 s and a total significance of about 178 sigma. The light curve comprises a multi-peaked structure with maxima at ~T0+1s and ~T0+9.5s.
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 45363
Subject
GRB 260810A: AstroSat CZTI detection of a long burst
Date
2026-08-12T14:03:40Z (13 days ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
A. Arya (IITB), A. Goyal (IITB), S.Salunke (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 260810A.
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2026-08-10 19:09:52.63 UTC. The measured peak count rate associated with the burst is 762 (+50, -55) counts/s above the background in the combined data of three quadrants (out of four), with a total of 3869 (+166, -185) counts. The local mean background count rate was 263 (+3, -3) counts/s. We measure a T90 of 13 (+1 , -2) s from the cumulative CZT light curve.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2026-08-10 19:09:44.03 UTC. The measured peak count rate associated with the burst is 1664 (+74, -88) counts/s above the background in the combined data of all quadrants, with a total of 7362 (+234, -330) counts. The local mean background count rate was 780 (+5, -4) counts/s. We measure a T90 of 12 (+1, -1) s from the cumulative Veto light curve.
CZTI data products like interactive and downloadable light curves for this GRB can be found at: https://astrosat.iucaa.in/cift/cift_products/524084975.53/S524084975.53_details.html
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb