{
  "bibcode": "2014GCN.15647....1X",
  "body": "L. P. Xin,   J. Y. Wei,   X. F. Wang, Y. L. Qiu, J. S. Deng,  J. Wang,  \r\nX. H. Han and C. Wu on behalf of EAFON report:\r\n\r\nWe began to observe GRB 131231A  (Sonbas et al., GCN 15640;\r\nXu et al., GCN 15641,15645; Malesani et al., GCN 15642; Singer et al. GCN 15643;\r\nHalpern GCN 15646) with Xinglong 0.8-m TNT telescope at 10:29:40 (UT) , \r\nJan. 1th, at 2014, about 29.73 hours after the burst.  \r\n12*300 sec B,V,R-band images were obtained. \r\n\r\nThe optical afterglow (Xu et al., GCN 15641)   was  clearly detected \r\nwith a magnitude of 18.97+/-0.1 mag in R band, calibrated by USNO B1.0 R2mag \r\nat the mean time of 29.73 hours after the burst.\r\n\r\nCompared with the report by Halpern GCN 15646, the brightness of this afterglow\r\ndecayed for 0.36 mag during the epoch between 22.55 hours and 29.73 hours after the burst.\r\n\r\nThis message may be cited.",
  "circularId": 15647,
  "createdOn": 1388581854000,
  "email": "xlp@bao.ac.cn",
  "subject": "GRB 131231A : xinglong TNT optical observation",
  "submitter": "L.P. Xin at NAOC  <xlp@bao.ac.cn>",
  "eventId": "GRB 131231A"
}