GCN Circular 42723
Subject
GRB 251116B: SVOM/VT optical upper limit
Event
Date
2025-11-17T16:17:41Z (4 days ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, Y. Xu, X. H. Han, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM) report on behalf of the SVOM/VT team.
SVOM/VT performed ToO observation on GRB 251116B (SVOM burst-id sb25111604, Pillas et al., GCN 42702). The observation started on 2025-11-17T01:05:38 UT (i.e. 9.55 hour post trigger) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously.
Inside the error box of SVOM/ECL (Pillas et al., GCN 42702) and the 6 sources reported by EP-FXT (Li et al., GCN 42709), we did not detect any new uncatalogued sources. Also no significant variation was found for the catalogued sources within EP-FXT's error circles. The 3 sigma upper limit magnitudes are derived as below:
Mid time | Band | Exposure Time | 3 sigma upper limit
10.0 hour VT_B 19*70 sec >23.3 mag
10.0 hour VT_R 22*70 sec >23.3 mag
Our result is consistent with the LCO's observation (Turpin et al., GCN 42706).
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.