2026-09-24T08:35:39.412Z | rev 0
SVOM/GRM team: Xing-Hao Luo, Yue Wang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: O. Godet (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 260920A (SVOM trigger reference: sb26092001) at 2026-09-20T10:32:35.000 (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45658) and AstroSat CZTI (A. Arya et.al., GCN#45672).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of muplti-pulses with a T90 of 23.5 +/-5 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn/gcn/2026/svgrb260920A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA = 293.0, Dec = -31.8, with a statistical uncertainty of 1.1 degrees, GCN #45658), is located at about 99 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view and nothing significant seen above 50 keV in the ECL light curve.
With this localization, the time-averaged spectrum from T0-11.5 to T0+22.0 s is best fitted by a power law function with an exponential high energy cutoff. The power law index is -1.05 +0.22/-0.19 and the cutoff energy, parameterized as Epeak, is 397 +150/-87 keV. The event fluence (10-1000 keV) in this time interval is (2.20 +0.19/−0.20)E-05 erg/cm^2.
The localization of GRB 260920A in the ‘Amati’ relation diagram is shown at:
https://www.bursthub.cn/gcn/2026/svgrb260920A_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: Xing-Hao Luo (IHEP) (luoxh@ihep.ac.cn)
GCN 45693: GRB 260920A: Glowbug gamma-ray detection
2026-09-22T15:40:18.193Z | rev 0
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 260920A, which was also detected by Fermi/GBM (GCN 45658) and AstroSat (GCN 45672).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-09-20 10:32:26.464 with a duration of 16.4 s and a total significance of about 32.3 sigma. The light curve comprises a complex multi-peak structure.
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 45672: GRB 260920A: AstroSat CZTI detection
2026-09-21T09:20:58.541Z | rev 0
A. Arya (IITB), A. Goyal (IITB), Harsha K. H. (IUCAA), S. Salunke(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 a GRB 260920A which was also detected by Fermi (Fermi GBM team, GCN Circ. 45658).
The source was 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 2026-09-20 10:32:38.06 UTC. The measured peak count rate associated with the burst is 234 (+37, -40) counts/s above the background in the combined data of all quadrants, with a total of 1301 (+278, -299) counts. The local mean background count rate was 306 (+4, -4) counts/s. We measure a T90 of 17 (+4, -3) s from the cumulative CZT light curve.
The source was 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 2026-09-20 10:32:37.72 UTC. The measured peak count rate associated with the burst is 750 (+60, -66) counts/s above the background in the combined data of all quadrants, with a total of 3370 (+383, -418) counts. The local mean background count rate was 694 (+4, -5) counts/s. We measure a T90 of 16 (+3, -2) 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/527596334.22/S527596334.22_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 45658: GRB 260920A: Fermi GBM Final Real-time Localization
2026-09-20T10:42:45.012Z | rev 0
The Fermi GBM team reports the detection of a likely LONG GRB
At 10:32:24 UT on 20 Sep 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260920A (trigger 811593149.787088 / 260920439).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 293.0, Dec = -31.8 (J2000 degrees, equivalent to J2000 19h 32m, -31d 48'), with a statistical uncertainty of 1.1 degrees.
The angle from the Fermi LAT boresight is 121.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260920439/quicklook/glg_skymap_all_bn260920439.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/bn260920439/quicklook/glg_healpix_all_bn260920439.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260920439/quicklook/glg_lc_medres34_bn260920439.gif
GCN 45657: EP260920a: SVOM/VT optical upper limits
2026-09-20T10:35:29.734Z | rev 0
H. L. Li, Y. N. Ma, C. Wu, L. P. Xin, Y. L. Qiu, Z. H. Yao, J. R. Xu, L. J. Chen, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. T. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team.
SVOM/VT performed ToO observation on the field of EP260920a (Ni et al., GCN 45649, GCN 45655). The observation started at 2026-09-20T00:48:38 UTC, about 43 minutes after trigger in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
No credible uncatalogued candidates were identified in our stacked images within the error box of EP-FXT (Ni et al., GCN 45655) compared to the Legacy Survey.
The following measurements are in the AB magnitude and are not corrected for Galactic extinction:
Mid time | Band | Exposure Time | 3-sigma upper limit
1.65 hr VT_B 72*50 sec > 24.0 mag
1.81 hr VT_R 93*50 sec > 24.0 mag
Our results are consistent with the non-detections from LCO (Liu et al., GCN 45653) and COLIBRÍ (Dornic et al., GCN 45654) .
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. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.