GCN 45169: sb26071506: SVOM detection of a X-ray transient

2026-07-15T17:05:29.603Z | rev 0 | event: sb26071506
Floriane Cangemi (APC), Alexis Coleiro (APC), Maria Grazia Bernardini (INAF-OAB, LUPM), Frederic Piron (LUPM), Nicolas Dagoneau (CEA), Andrea Saccardi (CEA) and Damien Turpin (CEA) report on behalf of the SVOM mission team:

At 2026-07-15T16:23:04 UTC (T0), SVOM/ECLAIRs triggered and located a X-ray transient (SVOM burst-id sb26071506).

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 4 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 9.24 in the [5-20] keV energy band over a time window of 327.68 seconds starting at 2026-07-15T16:18:58.

The localization of the best alert is R.A., Dec. 310.3570, -32.4133 degrees (J2000) with a 90% confidence level (C.L.) radius of 8.57 arcmin (including systematic error of 2 arcmin added in quadrature).

SVOM slewed to the burst.

SVOM/MXT began observing the field at 2026-07-15T16:27:08 UTC, 244 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 310.4508, -32.4345 degrees:
R.A. (J2000) = 20h41m48.18s
Dec. (J2000) = -32d26m04.34s
with a 90% C.L. radius of 29.15 arcseconds.

This location is 4.92 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received.

We note the presence of the high-proper motion star V* AT Mic in the error box of both ECLAIRs and MXT.

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. 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 Floriane Cangemi: cangemi@apc.in2p3.fr.
Please contact the BA by email if you require additional information.