GCN Circular 40213

Yifang Liang (PMO), Ziqi Wang (GXU), Wenjin Xie (NAOC), Stephane Schanne (CEA)  report on behalf of the SVOM mission team:


SVOM/ECLAIRs triggered on the X-ray transient labelled sb25042207 (SVOM burst-id sb25042207) starting at 2025-04-22T22:36:17 UTC (Tb).

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 (SNR) of 7.01 in the 5-8 keV energy band over a time window of 1310.72 seconds starting at Tb.

The localization of the best alert is R.A., Dec 194.9273, 27.7745 degrees:
RA (J2000) = 12h59m42.56s
Dec (J2000) = 27d46m28.13s
with a 90% C.L. radius of 11.17 arcmin (including systematic error of 2 arcmin added in quadrature).

We notice the presence of many X-ray candidate sources inside the error region, including 2 QSOs, as well as 2 nearby AGNs including Mrk 60.

SVOM did not slew to this transient because it did not exceed the slew threshold. SVOM follow-up observations will be 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.

The Burst Advocate (BA) on shift for this transient is Yifang Liang: yfliang@pmo.ac.cn
Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst.