GCN Circular 44649

M. Brunet, O. Godet (IRAP), H. Goto (RIKEN/CEA), A. Saccardi (CEA/Irfu) report on behalf of the SVOM mission team:

At 2026-05-16T20:39:50 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260516D (SVOM burst-id sb26051616).

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 1 alert. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 6.73 in the [5-20] keV energy band over a time window of 81.92 seconds starting at 2026-05-16T20:38:28.

The localization of the best alert is R.A., Dec. 233.849, 6.373 degrees:
R.A. (J2000) = 15h35m23.71s
Dec. (J2000) = 6d22m21.34s
with a 90% confidence level (C.L.) radius of 11.62 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.

A Svom ToO has been scheduled.

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 Andrea Saccardi (CEA): andrea.saccardi@cea.fr
Please contact the BA by email if you require additional information.