GCN Circular 40697

L. Zhang (IHEP), Y.-D. Hu (GXU), X.-L. Chen (YNU), N. Dagoneau (CEA), U. Jacob (LUPM), C. Van Hove (IJCLab) on behalf of the SVOM mission team.

At 2025-06-12T10:27:22 UTC (T0), SVOM/ECLAIRs triggered and located the X-ray transient sb25061207 (SVOM burst-id sb25061207).

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 3 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 7.34 in the [5-20] keV energy band over a time window of 40.96 seconds starting at 2025-06-12T10:27:02.

The localization of the best alert is R.A., Dec. 197.9873, 0.0214 degrees:
R.A. (J2000) = 13h11m56.95s
Dec. (J2000) = +00d01m17.04s
 with a 90% confidence level (C.L.) radius of 10.68 arcmin (including systematic error of 2 arcmin added in quadrature).

The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/sb25061207.png

SVOM slewed to the burst.

MXT began observing the field at 2025-06-12T10:31:00 UTC, ~ 4 min after T0. Using onboard processed data, no source was detected in 750 seconds.
The MXT team is waiting for the full dataset to detect and localise the possible MXT counterpart.

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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. 

The Burst Advocate (BA) on shift for this alert is Y.-D. Hu : hyd@gxu.edu.cn.
Please contact the BA by email if you require additional information.