GCN Circular 45619

Donghua Zhao (NAOC), Clara Plasse (HKU), Yun Wang (UCB; PMO), Yehao Cheng(YNU), Diego Götz (CEA) report on behalf of the SVOM mission team:

At 2026-09-18T03:47:56 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260918A (SVOM burst-id sb26091801).

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 Image Trigger (IMT), which produced a sequence of 2 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 7.60 in the [8-120] keV energy band over a time window of 40.96 seconds starting at 2026-09-18T03:47:15.

The localization of the best alert is R.A., Dec. 354.8016, -8.9544 degrees:
R.A. (J2000) = 23h39m12.39s
Dec. (J2000) = -8d57m15.73s
 with a 90% confidence level (C.L.) radius of 10.33 arcmin (including systematic error of 2 arcmin added in quadrature).

SVOM slewed to the burst. 
The SVOM/MXT team is waiting for the full dataset to detect and localise the possible SVOM/MXT counterpart. 
SVOM/VT began observing the field after the slew. The observations will be reported in circulars.


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 Yun Wang: wangyun@pmo.ac.cn.
Please contact the BA by email if you require additional information.