{
  "submittedHow": "web",
  "submitter": "Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>",
  "circularId": 44769,
  "subject": "GRB 260601B/EP260601a: SVOM/VT optical observations",
  "eventId": "GRB 260601B",
  "format": "text/plain",
  "createdOn": 1780413819159,
  "body": "H. L. Li, C. Wu, Y. L. Qiu, L. P. Xin, Y. N. Ma, Z. H. Yao, 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) and J. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team.\n\nSVOM/VT performed ToO observations to the field of GRB 260601B/EP260601a triggered by Einstein Probe (Yang et al., GCN 44766), which was also detected by GECAM-B (Yu et al., GCN 44767; Wang et al., GCN 44768). The VT observation started at 2026-06-02T08:56:14 UTC, 13.72 hours post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously.\n\nThe optical counterpart (Liu et al., GCN 44764; Guelfand et al., GCN 44765) 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\n14.65 h    VT_B     76*50 s     23.4  +/- 0.3  mag\n14.63 h    VT_R     62*50 s     21.43 +/- 0.15 mag\n\nThe VT red color suggests a moderate redshift ~ 4 (Wang et al.,2020).\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."
}