GCN Circular 44787

Donghua ZHAO, Wenjin Xie (NAOC), Ruizhi Li (YNAO), Ziming Wang (BNU) report on behalf of the SVOM mission team:

At 2026-06-03T05:38:16 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260603A (SVOM burst-id sb26060303).

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 13 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 15.29 in the [5-20] keV energy band over a time window of 81.92 seconds starting at 2026-06-03T05:37:55.

The localization of the best alert is R.A., Dec. 233.1366,40.0801 degrees:
R.A. (J2000) = 15h32m32.79s
Dec. (J2000) = 40d04m48.22s
 with a 90% confidence level (C.L.) radius of 5.42 arcmin (including systematic error of 2 arcmin added in quadrature).

One high proper motion star named TYC 3055-1389-1 is at 194.45 arcsec away.
 
Due to a ToO-EX in performance, no immediate slew was performed on this burst.

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 Ruizhi Li: liruizhi@ynao.ac.cn. Please contact the BA by email if you require additional information.