{
  "bibcode": "2020GCN.29159....1Z",
  "body": "Z.P. Zhu (NAOC, HUST), S.Y. Fu, M. Zhang, X. Liu, D. Xu (NAOC), X. Gao (Urumqi \nNo.1 Senior High School), J.Z. Liu (XAO) report:\n\nWe observed the field of GRB 201223A (Gropp et al., GCN 29158) using the \nNEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. \nObservations automatically started at 18:01:14 UT on 2020-12-23, i.e., \n168 s after the BAT trigger. We obtained a series of 2x40s, 4x60s and \n12x90s frames in the Sloan r-filter, and observations are ongoing.\n\nAn uncatalogued decaying optical transient is detected at the Swift/UVOT \nposition (Gropp et al., GCN 29158), which is thus concluded to be the \noptical afterglow of burst. The afterglow has r = 15.67 +/- 0.01 mag in \nour first image, calibrated with nearby PS1 stars.\n\n[GCN OPS NOTE(24Dec2020)  Per author's request, M. Zhang was added\nto the author list.]",
  "circularId": 29159,
  "createdOn": 1608749930000,
  "email": "dxu@nao.cas.cn",
  "subject": "GRB 201223A: Nanshan/NEXT early optical afterglow detection",
  "submitter": "Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>",
  "eventId": "GRB 201223A"
}