TITLE: GCN CIRCULAR NUMBER: 15146 SUBJECT: GRB 130831A : Xinglong 60cm optical observation DATE: 13/08/31 19:39:25 GMT FROM: L.P. Xin at NAOC L. P. Xin, X. H. Han, Y. L. Qiu, J. Y. Wei, J. Wang, J. S. Deng and C. Wu on behalf of EAFON report: We began to observe GRB 130831A (Hagen et al. GCN 15139) with Xinglong 60cm telescope at 15:42:00 (UT), about 2.7 hours after the burst. A series of white and R-band images were obtained. The OT reported by (Hagen et al. GCN 15139, Guidorzi et al. GCN 15140, Xu et al. GCN 15142; Yoshii et al. GCN 15143, Cucchiara et al. GCN 15144) was detected in all images. The brightness of this OT was about R=16.6 mag at 2.7 hours after the burst, calibrated by USNO B1.0 R2 mag. This message may be cited.