{
  "body": "H. L. Li, C. Wu, Y. L. Qiu, J. R. Xu, L. P. Xin, Y. N. Ma, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA/Irfu), R. Z. Li (YNAO) and Z. M. Wang (BNU) report on behalf of the SVOM/VT team.\n\nSVOM/VT performed ToO observations to the field of GRB 260603A triggered by SVOM/ECLAIRs (sb26060303, Zhao et al., GCN 44787). The observation started at 2026-06-03T07:04:07 UTC, 1.44 hours post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously.\n\nThe optical counterpart (Guelfand et al., GCN 44791; GCN 44797) was detected by VT in both channels. The following measurements are in the AB magnitude without correction for Galactic extinction:\n\nMid time | Band | Exposure Time | Brightness\n1.78 h    VT_B     36*70 s     22.08 +/- 0.12 mag\n1.78 h    VT_R     30*70 s     21.37 +/- 0.10 mag\n3.41 h    VT_B     36*70 s     22.40 +/- 0.14 mag\n3.40 h    VT_R     31*70 s     21.74 +/- 0.11 mag\n\nThe source showed a fading slope of about -0.53 during the observations above.\n\nThe 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.",
  "submitter": "Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>",
  "circularId": 44799,
  "eventId": "GRB 260603A",
  "subject": "GRB 260603A: SVOM/VT optical observations",
  "submittedHow": "web",
  "createdOn": 1780488059712,
  "format": "text/plain"
}