GCN Circular 44212
Subject
GRB 260330B: SVOM/VT further optical observation
Event
Date
2026-04-04T05:24:23Z (15 days ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
H. L. Li, L. P. Xin, Y. N. Ma, C. Wu, Z. H. Yao, Y. L. Qiu, J. R. Xu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team.
SVOM/VT performed a second ToO observation of the field of GRB 260330B detected by SVOM/ECLAIRs (sb26033003, Lan et al., GCN 44157), SVOM/GRM (Lan et al., GCN 44157) and Fermi/GBM with sub-threshold detection (Trigg et al., GCN 44159). The observations started at 2026-04-03T12:56:07 UTC, approximately 3.94 days post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously.
The optical candidate (Li et al., GCN 44205) was detected in VT_R. The measurements in AB magnitude are as follows:
Mid time | Band | Exposure Time | Brightness
4.019 d VT_R 82*70 sec 22.7+/-0.2 mag
4.019 d VT_B 87*70 sec >24.0 mag
Our photometry was in the AB magnitude and was not corrected for Galactic extinction. We note the current brightness may be contaminated by the catalogued extended source (Li et al., GCN 44205).
Combined with our previous observations (Li et al., GCN 44205), the candidate brightened and then faded in our observations.
Further observations are encouraged to confirm the nature of this source.
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.