{
  "bibcode": "2020GCN.28719....1X",
  "body": "D. Xu (NAOC), Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu (NAOC), X. Gao \n(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:\n\nWe observed the field of GRB 201020B detected by Fermi/GBM, Fermi/LAT, \nand AGILE (Fermi GBM team, GCN 28702; Malacaria et al., GCN 28710; \nArimoto et al., GCN 28716; Ursi et al., GCN 28714), starting at 12:35:28 \nUT on 2020-10-21, i.e., 0.7927 day after the Fermi trigger. Photometry \nhas been done in Sloan r-filter with 60s for each exposure, and \nobservations are ongoing.\n\nThe optical transient reported by MASTER (Lipunov et al., GCN 28718) is \nclearly detected in our single image at improved coordinates\n\nR.A. (J2000) = 5:01:52.80\nDec. (J2000) = +77:04:06.23\n\nwith a positional uncertainty of ~0.5 arcsec. It has decayed to m_r = \n19.0 +/- 0.1 at T_mid = 0.7944 day post-trigger, calibrated with nearby \nPS1 stars.\n\nBased on the quick decay behaviour, we confirm that the source is very \nlikely the afterglow of the burst.",
  "circularId": 28719,
  "createdOn": 1603286448000,
  "email": "dxu@nao.cas.cn",
  "subject": "GRB 201020B: Nanshan/NEXT optical afterglow confirmation",
  "submitter": "Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>",
  "eventId": "GRB 201020B"
}