GCN Circular 45606

Hanrui He (PMO), Wenjin Xie (NAOC), Chao Wu (NAOC), Kuan Liu (USTC), Clara Plasse (HKU) , Hatsune Goto (RIKEN, CEA), Stephane Schanne (CEA)  report on behalf of the SVOM mission team:

At 2026-09-17T03:52:21 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260917B (SVOM burst-id sb26091701). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.

The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 8 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 8.95 in the [8-120] keV energy band over a time window of 20.40 seconds starting at 2026-09-17T03:52:11.

The localization of the best alert is R.A., Dec. 46.8646, 25.4836 degrees:
R.A. (J2000) = 3h07m27.50s
Dec. (J2000) = 25d29m00.99s
 with a 90% confidence level (C.L.) radius of 8.84 arcmin (including systematic error of 2 arcmin added in quadrature).

SVOM slewed to the burst. MXT and VT began observing the field after the slew. The analysis of the data will be published in a future circular.

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 Chao Wu: cwu@bao.ac.cn
Please contact the BA by email if you require additional information.