{
  "bibcode": "2022GCN.32355....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 220708B detected by Swift/BAT-GUANO \n(Tohuvavohu et al., GCN 32345) using the NEXT-0.6m telescope located at \nNanshan, Xinjiang, China. We obtained 10x200 s frames in the Sloan \nr-band and 9x200 s frames in Sloan z-band, starting at 19:15:57.859 UT \non 2022-07-08,i.e.,17.15 hr after the BAT trigger.\n\nNo optical source is detected in our stacked images at the  XRT \nafterglow position (Osborne et al., GCN 32350), with upper limits as \nfollows:\n\nT_mid-T0 (hr)    Filter   Upper limit(3-sigma)\n    17.42               r         >21.60\n    17.96               z         >19.54\n\ncalibrated with the nearby PanSTARRS field and not corrected for \nGalactic extinction.",
  "circularId": 32355,
  "createdOn": 1657336700000,
  "email": "dxu@nao.cas.cn",
  "subject": "GRB 220708B: Nanshan/NEXT optical upper limits",
  "submitter": "Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>",
  "eventId": "GRB 220708B"
}