GRB 260225D
GCN Circular 43890
Subject
GRID detection of GRB 260225D
Date
2026-03-01T13:20:06Z (9 days ago)
From
GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>
Via
Web form
Longhao Li, Chenyu Wang, Zirui Yang report on behalf of the GRID Collaboration:
GRID reports the detection of GRB 260225D, which was also observed by Glowbug (GCN #43856) and SVOM/GRM(GCN #43885).
The event triggered GRID at T0 = 2026-02-25 19:51:28.7 UTC and was detected by both GRID-09B and GRID-11B, with a weaker signal observed by GRID-11B. Temporal analysis based on GRID-09B data yields a burst duration of T90 = 1.96 ± 0.08 s in the 30–2000 keV energy range.
At present, only the GRID light curve is available. No spectral analysis is reported at this stage. The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB260225D/GRID_260225D_ltcv.pdf
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
GCN Circular 43885
Subject
GRB 260225D: SVOM/GRM observation
Date
2026-03-01T08:05:24Z (9 days ago)
From
zhangjinpeng@ihep.ac.cn
Via
Web form
SVOM/GRM team: Jin-Peng Zhang, Zheng-Hang Yu, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Frédéric Daigne (IAP), Olivier GODET (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 260225D (SVOM trigger reference: sb26022503) at 2026-02-25T19:51:30.000 (T0), which is also detected by Konus-Wind (Trig_Time 19:51:32.84), Glowbug (C.C. Cheung et al., GCN #43856) and GRID.
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of two pulses with a T90 of 2.0 +1.0/-0.6 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb260225D.png
In addition, the position of this burst, according to Glowbug localization (RA = 94.7, Dec = 13.8, C.C. Cheung et al., GCN #43856), is located at about 93 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 T0-2.0 to T0+4.0 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.12 +0.18/-0.15 and the cutoff energy, parameterized as Epeak, is 700 +480/-250 keV. The event fluence (10-1000 keV) in this time interval is (8.5 +0.8/-0.9)E-07 erg/cm^2.
The localization of GRB 260225D in the 'Amati' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb260225D_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: Jin-Peng Zhang (IHEP) (zhangjinpeng@ihep.ac.cn)
GCN Circular 43856
Subject
GRB 260225D: Glowbug gamma-ray detection of a likely short burst
Date
2026-02-26T20:53:48Z (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 260225D, which was also detected by Konus-Wind (Trig_Time 19:51:32.84) and SVOM/GRM (sb26022503).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-02-25 19:51:28.768 with a duration of 1.98 s and a total significance of about 62 sigma. The light curve comprises two primary peaks at ~T0+0.2s and +1.6s.
The best-fit localization is RA, Dec. (J2000, deg) = 94.7, 13.8 with a radius of 7.0 deg (95% confidence), with a highly uncertain systematic uncertainty.
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
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