GCN Circular 42148

N. A. Webb, O. Godet, S. Guillot (IRAP), F. Lacreu (IAP) report on behalf of the SVOM mission team


At 2025-10-07T19:43:23 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251007B (SVOM burst-id sb25100703), also detected by Swift/BAT (GCN #42147
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 , Melandri et al. 2025).


The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.


The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 7 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 9.53 in the [8-50] keV energy band over a time window of 20.40 seconds starting at 2025-10-07T19:42:57.


The localization of the best alert is R.A., Dec. 101.997, -10.279 degrees:

R.A. (J2000) = 6h47m59.29s

Dec. (J2000) = -10d16m42.81s

with a 90% confidence level (C.L.) radius of 8.33 arcmin (including systematic error of 2 arcmin added in quadrature).


The SVOM/ECLAIRs light curve showed a single peak structure with a T90 duration of about 23.26 (-8.032 +4.41) s.


The platform did not slew to the source. No observations could be performed in the X-rays by SVOM/MXT nor in the optical with 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 Natalie Webb: natalie.webb@irap.omp.eu.

Please contact the BA by email if you require additional information.