GRB 260825A
GCN Circular 45469
Subject
GRB 260825A: SVOM/GRM observation of a long burst
Date
2026-08-30T10:14:34Z (3 days ago)
From
Jin-Ye Luo <jy_luo2002@163.com>
Via
Web form
SVOM/GRM team: Jin-Ye Luo, Chen-Wei Wang, Yue Wang, Hao-Xuan Guo, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Maria Grazia Bernardin (INAF)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 260825A at 2026-08-25T13:07:19.000 (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45439), AstroSat/CZTI (Harsha K. H. et al., GCN #45466), and GECAM-B (Jin-Ye Luo et. al., GCN #45468).
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 47 +8/-5 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn/gcn/2026/svgrb260825A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA = 88.3 deg, Dec = -1.2 deg, Error = 5.7 deg, GCN #45439), is located at about 62 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-9 to T0+38 s is best fitted by a power law function. The power law index is -1.06 +0.6/-0.06. The event fluence (10-1000 keV) in this time interval is (1.26 +0.07/−0.07)E-05 erg/cm^2.
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-Ye Luo (IHEP) (luojy@ihep.ac.cn)
GCN Circular 45468
Subject
GRB 260825A: GECAM-B observation
Date
2026-08-30T09:38:29Z (3 days ago)
From
jy_luo2002@163.com
Via
Web form
Jin-Ye Luo, Chen-Wei Wang, Yue Wang, Hao-Xuan Guo, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered on-ground by GRB 260825A at 2026-08-25T13:07:19.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45439) and AstroSat/CZTI (Harsha K. H. et al., GCN #45466).
According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 45 +7/-13 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn/gcn/2026/gecambgrb260825A.png
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 45466
Subject
GRB 260825A: AstroSat CZTI detection
Date
2026-08-29T08:02:52Z (4 days ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
Harsha K. H. (IUCAA), S. Salunke(IUCAA), A. Arya (IITB), A. Goyal (IITB), G. Waratkar (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 a long duration GRB 260825A which was also detected by Fermi (Fermi GBM team, GCN Circ. 45439).
The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-08-25 13:07:14.95 UTC. The measured peak count rate associated with the burst is 161 (+58, -1) counts/s above the background in the combined data of all quadrants, with a total of 7311 (+1106, -1122) counts. The local mean background count rate was 660 (+2, -2) counts/s. We measure a T90 of 206 (+23, -17) s from the cumulative Veto light curve. The duration of T90 is long due to a small flare at 2026-08-25 13:09:11.95 UTC. If this is not related to the burst, the primary has T90 of 63 (+6, -26) s.
CZTI data products like interactive and downloadable light curves for this GRB can be found at: https://astrosat.iucaa.in/cift/cift_products/525359231.45/S525359231.45_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
GCN Circular 45439
Subject
GRB 260825A: Fermi GBM Final Real-time Localization
Date
2026-08-25T13:17:43Z (8 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 LONG GRB
At 13:07:15 UT on 25 Aug 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260825A (trigger 809356040.919172 / 260825547).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 88.3, Dec = -1.2 (J2000 degrees, equivalent to J2000 05h 53m, -1d 11'), with a statistical uncertainty of 5.7 degrees.
The angle from the Fermi LAT boresight is 95.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260825547/quicklook/glg_skymap_all_bn260825547.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/bn260825547/quicklook/glg_healpix_all_bn260825547.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260825547/quicklook/glg_lc_medres34_bn260825547.gif