TITLE: GCN CIRCULAR NUMBER: 18515 SUBJECT: GRB 151027A : Xinglong TNT optical observation DATE: 15/10/28 14:37:57 GMT FROM: L.P. Xin at NAOC L. P. Xin, X. F. Wang, J. Y. Wei, Y. L. Qiu, J. S. Deng, J. Wang, X. H. Han and C. Wu on behalf of EAFON report: We observed GRB 151027A (Maselli et al., GCN 18478) with Xinglong 0.8-m TNT telescope at 2015-10-27 and 2015-10-28. The optical afterglow (Maselli et al., GCN 18478; Zheng & Filippenko GCN 18479; Elenin et al., GCN 18480; Perley & Cenko GCN 18481; Xu et al, 18485; Zhang et al., GCN 18513) was clearly detected in our multi-band images. The brightness of the optical afterglow is decayed for about 2.5 mag in R-band during our observations as shown in follows: ============================== Date Time(UT) filter mag merr 2015-10-27 11:21:59 R 16.2 0.1 2015-10-28 11:04:00 R 18.7 0.1 ============================== Calibrated by the USNO B1.0 R2 mag More observations are encouraged. The message may be cited.