GCN Circular 44071

M. Brunet, O. Godet (IRAP) report on behalf of the SVOM mission team:

At 2026-03-21T18:12:08 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260321A (SVOM burst-id sb26032123).

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 9.37 in the [8-120] keV energy band over a time window of 40.96 seconds starting at 2026-03-21T18:11:48.

The localization of the best alert is R.A., Dec. 219.574, 31.674 degrees:
R.A. (J2000) = 14h38m17.65s
Dec. (J2000) = 31d40m28.18s
 with a 90% confidence level (C.L.) radius of 8.45 arcmin (including systematic error of 2 arcmin added in quadrature).

This burst also triggered SVOM/GRM at 2026-03-21T18:12:08 with an SNR of 10.9.
The SVOM/GRM light curve showed a multiple peak structure with a T90 duration of about 113.02 -18.24 / +74.15 (8-1100 keV).

SVOM slewed to the burst.

No X-ray observation could be performed by SVOM/MXT for the time being. No optical observation could be performed by SVOM/VT for the time being.

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 Marius Brunet: mbrunet@irap.omp.eu.
Please contact the BA by email if you require additional information.