GRB 260827A

Zheng-Hang Yu and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:
 
At 2026-08-27T10:43:00.600 (T0), Insight-HXMT/HE detected GRB 260827A, which is also detected by Fermi/GBM (Fermi GBM team, GCN #45453
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 ), Glowbug (C.C. Cheung et al., GCN #45475
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 ), and SVOM/GRM (Yu et al., GCN #45479
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 ).
 
The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 1.6 +1.6/-0.7 s. The 1 s peak rate, measured from T0-0.85 s, is 932 cnts/sec. Insight-HXMT/HE detected a total of 1396 counts from this burst.
 
The Insight-HXMT/HE light curve can be found here:
https://www.bursthub.cn/gcn/2026/hxmtgrb260827A.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://www.hxmt.org

SVOM/GRM team: Zheng-Hang Yu, Chen-Wei Wang, Yue Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)

SVOM/ECLAIRs team: Frédéric Daigne

Report on behalf of the SVOM team:

SVOM/GRM was triggered in-flight by GRB 260827A at 2026-08-27T10:43:00.700 (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45453
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 ).

With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple pulses with a T90 of 1.7 +0.6/-0.3 s in the 15-5000 keV band.

The SVOM/GRM light curve can be found here:
https://www.bursthub.cn/gcn/2026/svgrb260827A.png

In addition, the position of this burst, as determined by Fermi/GBM (RA = 247.9, Dec = -53.5, Error = 2.4 degrees, GCN #45453
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 ), is located at about 105 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. Nevertheless, ECLAIRs detected the GRB through the shield above 50 keV. 

With this localization, the time-averaged spectrum from T0-1 to T0+2 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.49 +0.24/-0.27 and the cutoff energy, parameterized as Epeak, is 431 +91/-64 keV. The event fluence (10-1000 keV) in this time interval is (4.61 +0.32/−0.34)E-06 erg/cm^2. 

The localization of GRB 260827A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn/gcn/2026/svgrb260827A_amati.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/GRM point of contact for this burst is: Zheng-Hang Yu (IHEP) (zhyu@ihep.ac.cn)

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 260827A, which was also detected by Fermi/GBM (GCN 45453
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 ).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-08-27 10:42:58.640 with a duration of 2.6 s and a total significance of about 11.3 sigma. The light curve 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
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[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.

The Fermi GBM team reports the detection of a likely LONG GRB

At 10:42:59 UT on 27 Aug 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260827A (trigger 809520184.770226 / 260827447).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 247.9, Dec = -53.5 (J2000 degrees, equivalent to J2000 16h 31m, -53d 30'), with a statistical uncertainty of 2.4 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/bn260827447/quicklook/glg_skymap_all_bn260827447.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/bn260827447/quicklook/glg_healpix_all_bn260827447.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260827447/quicklook/glg_lc_medres34_bn260827447.gif