{
  "bibcode": "2022GCN.31475....1F",
  "body": "S.Y. Fu (NAOC), Z.P. Zhu (NAOC,HUST), X. Liu, S.Q. Jiang, D. Xu (NAOC), \nX. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:\n\nWe observed the field of GRB 220117B detected by Swift (Melandri et al., \nGCN 31468) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, \nChina. Observations automatically started at 20:07:36 UT on 2022-01-17, \ni.e., 128 s after the BAT trigger, and a series of 40 s, 60 s, 90 s \nframes were obtained in the Sloan r-band.\n\nNo uncatalogued optical transient is detected in our stacked images at \nthe Swift-XRT position (GCN 31468), down to limiting magnitudes of \nr~18.5, calibrated with the nearby PanSTARRS field.",
  "circularId": 31475,
  "createdOn": 1642476324000,
  "email": "dxu@nao.cas.cn",
  "subject": "GRB 220117B: Nanshan/NEXT optical upper limit",
  "submitter": "Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>",
  "eventId": "GRB 220117B"
}