GRB 260913A
GCN Circular 45561
Subject
GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
Date
2026-09-14T08:34:42Z (2 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
M. Brunet (IRAP), S. Schanne (CEA), W.-J. Xie (NAOC), X. Tian (GXU), W.-L. Zhang (PMO), report on behalf of the SVOM mission team:
At 2026-09-13T07:38:21 SVOM issued an alert with burst-id: sb26091302.
The following circulars have been published regarding this event: GCN 45557, GCN 45558, GCN 45559, with the event labelled as GRB 260913A.
This event is not a GRB of astrophysical origin. After reprocessing the data with the full telemetry, this trigger is no longer considered as an astrophysical source but is due to coding noise from the Crab in the field of view.
We apologize for any inconvenience this may have caused.
The Burst Advocate (BA) on shift for this alert is Wenlong Zhang: wlzhang@pmo.ac.cn.
Please contact the BA by email if you require additional information.
GCN Circular 45558
Subject
GRB 260913A: SVOM/C-GFT optical upper limit
Date
2026-09-13T16:19:08Z (3 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
Y.X Guan (GXU), Z. Kang (CHO), C. Wu , L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC), X. Tian (GXU), W.-L. Zhang (PMO) report on behalf of the SVOM/C-GFT team:
We observed the field of GRB 260913A detected by SVOM/ ECLAIRs (Yang et al., GCN 45557) with LATIOS on SVOM/C-GFT. Observations started at 2026-09-13T14:27:59 UTC, ~ 6.83 hr after the trigger.
We obtained follow-up imaging in g, r, and i bands. After preliminary analysis, no credible candidate was detected within the error box provided by SVOM/Eclairs(Yang et al., GCN 45557) in our images. We measure the following upper limit calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:
g > 20.3 AB (5-sigma, mid-time 7.22 hr after the trigger).
r > 20.2 AB (5-sigma, mid-time 7.48 hr after the trigger).
i > 20.1 AB (5-sigma, mid-time 6.96 hr after the trigger).
We thank the observation assistants B.-W. Li and H.-X. Xue at Jilin observatory for their excellent support.
The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcmin x 21 arcmin FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching.
GCN Circular 45557
Subject
GRB 260913A: SVOM detection of a faint burst
Date
2026-09-13T08:42:43Z (3 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
J. Yang (ZZU), A. Li (BNU), X. Tian (GXU), W.-L. Zhang (PMO), C. Lachaud (APC), S. Schanne (CEA/IRFU), W.-J. Xie (NAOC) report on behalf of the SVOM mission team:
At 2026-09-13T07:38:21 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260913A (SVOM burst-id sb26091302).
The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.
The burst was only detected by the Count-Rate Trigger (CRT), which produced a sequence of 2 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 8.29 in the [8-50] keV energy band over a time window of 20.40 seconds starting at 2026-09-13T07:38:11.
The localization of the best alert is R.A., Dec. 105.2715, 58.8936 degrees:
R.A. (J2000) = 7h01m05.17s
Dec. (J2000) = 58d53m36.84s
with a 90% confidence level (C.L.) radius of 9.50 arcmin (including systematic error of 2 arcmin added in quadrature).
Due to the detection significance being below the slew threshold, no immediate slew was performed on this burst. Due to the solar angle constraints, this burst is not observable by SVOM. We noticed the presence of the Crab in the ECLAIRs field of view.
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE.
The Burst Advocate (BA) on shift for this alert is Wenlong Zhang: wlzhang@pmo.ac.cn.
Please contact the BA by email if you require additional information.