TITLE: GCN CIRCULAR NUMBER: 6924 SUBJECT: GRB 071010B: Optical observations of EST DATE: 07/10/16 16:03:33 GMT FROM: L.P. Xin at NAOC We observed the afterglow (Oksanen, GCN 6873) of GRB 071010B (Markwardt et al., GCN 6871) with the EST 1m telescope at Xinglong Observatory started from 19:07:59(UT) Oct.11. Totally 11*600s V-band images were obtained. With the calibration data reported by Henden (GCN 6909) we derived the afterglow had a magnitude V=20.75 +/- 0.05 with mid-time 23.314 hours after the burst. Compared with the V-band magnitude of Daniel Kocevski (GCN 6919), we found the V-band magnitude of the afterglow decayed deeply about 1 magnitude after about 5 hours. This message may be cited.