{
  "bibcode": "2022GCN.32335....1J",
  "body": "S.Q. Jiang (NAOC), Z.P. Zhu (NAOC,HUST), S.Y. Fu , X. Liu, D. Xu (NAOC), \nX. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:\n\nWe observed the field of GRB 220706A detected by Swift (D'Ai et al., GCN \n32329) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, \nChina. We obtained 7x200 s frames in the Sloan r-band and 5x200 s frames \nin the Sloan z-band, starting at 20:21:09 UT on 2022-07-06, i.e., 4.2 hr \nafter the BAT trigger.\n\nNo optical source is detected in our stacked images at the enhanced XRT \nposition (Goad et al., GCN 32333), with upper limits as follows:\n\nT_mid-T0 (hr)    Filter   Upper limit(3-sigma)\n    4.41                 r          >20.7\n    4.79                 z          >18.8\n\ncalibrated with the nearby PanSTARRS field and not corrected for \nGalactic extinction.",
  "circularId": 32335,
  "createdOn": 1657161918000,
  "email": "dxu@nao.cas.cn",
  "subject": "GRB 220706A: Nanshan/NEXT optical upper limits",
  "submitter": "Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>",
  "eventId": "GRB 220706A"
}