GCN Circular 40645
Subject
GRB 250605A: SVOM/VT optical upper limit
Date
2025-06-06T15:40:20Z (a day ago)
Edited On
2025-06-06T15:42:57Z (a day ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Z. H. Yao, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team.
SVOM/VT conducted ToO follow-up observations of the GRB 250605A (Gupta et al., GCN 40633, Melandri et al., GCN 40644). The observation started on 2025-06-06T05:02:39 UT in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
No uncatalogued sources are detected in single or stacked images within the Swift/XRT error box (Evans et al., GCN 40642) and the possible optical candidate reported by Gompertz et al. (GCN 40634). The 3 sigma limit magnitudes are derived as below:
Mid time | Band | Exposure Time | 3 sigma limit magnitude
11.28 hour VT_B 59*70 sec >23.6 mag
11.28 hour VT_R 59*70 sec >23.6 mag
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.