sb25022102
GCN Circular 39399
Subject
SVOM trigger sb25022102 is not an astrophysical event
Date
2025-02-21T08:39:54Z (2 years ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
R.-Z. Li (YNAO, CAS), Y. Wang (PMO, CAS), J.-X. Cao, D.-F. Kong (GXU), W.-J. Xie, D.-H. Zhao (NAOC), M. Moita (CEA), L. Zhang (IHEP) report
on behalf of the SVOM mission team.
At 2025-02-21T02:57:58 SVOM issued an alert with the burst_id sb25022102, see also (Li et al, GCN 39398).
This event is no longer considered as an astrophysical event and is likely a false detection due to the presence of Sco X-1 in the edge (partially coded) of the ECLAIRs field of view.
We apologize for any inconvenience this may have caused.
The Burst Advocate (BA) on shift for this event is R.-Z. Li (YNAO, CAS): liruizhi@ynao.ac.cn. Please contact the BA by email if you require any additional information.
GCN Circular 39398
Subject
SVOM/sb25022102: SVOM detection of an X-ray transient
Date
2025-02-21T04:52:41Z (2 years ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
R.-Z. Li (YNAO, CAS), Y. Wang (PMO, CAS), J.-X. Cao, D.-F. Kong (GXU), W.-J. Xie, D.-H. Zhao (NAOC), M. Moita (CEA), L. Zhang (IHEP) report on behalf of the SVOM mission team:
The SVOM/ECLAIRs telescope triggered and located a soft X-ray transient (SVOM burst-id sb25022102) starting at 2025-02-21T02:57:58.938 UTC (Tb).
The following trigger information was received on the ground with low-latency by the SVOM VHF Alert Network.
The burst was detected by the Count-Rate Trigger (CRT) mode and 2 alerts were produced with a best signal-to-noise ratio of 9.66 in the 8-120 keV energy band over a time window of 20.48 second starting at Tb.
The localization of the alert is R.A., Dec = 231.472, -17.950 degrees:
RA (J2000) = 15:25:53.18
Dec (J2000) = -17:56:58.32
with a 90% C.L. radius of 8.22 arcmin (including systematic error of 2 arcmin added in quadrature).
We notice that this error-box contains an X-ray source which could produce such a transient, which is 1RXS J152553.0-174943 in Simbad, located at 7.3 arcmin distance.
The SVOM/GRM lightcurve could be find the link below:
https://www.bursthub.cn//admin/static/svgrb20250221A.png
This trigger reached the slew threshold, hence automatic slew was performed. No X-ray sources were found in the VHF data of SVOM/MXT at 1.22 hours after the trigger. A SVOM ToO has been scheduled.
The Space 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 burst is R.-Z. Li (YNAO, CAS):
liruizhi@ynao.ac.cn
Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst.