TITLE: GCN CIRCULAR NUMBER: 17631 SUBJECT: GRB 150323C : Xinglong TNT optical observation DATE: 15/03/24 05:34:21 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 began to observe GRB 150323C (Amaral-Rogers et al., GCN 17621) with Xinglong 0.8-m TNT telescope at 2015-03-23, 17:07:27(UT), about 126 sec after the Swift trigger time. The new source within XRT circle (Amaral-Rogers et al., GCN 17621 ) reported by Xu et al., ( GCN 17625 ) was clearly detected in our coadded images. Preliminary analysis shows that the brightness of this optical transient in R band is rising from 21.6 to 20.2 and then decaying, indicating that this source is the optical afterglow of the burst. All the magnitudes are calibrated by a nearby USNO B1.0 object ( RA: 16:50:26 DEC: 50:11:48, R2=16.47mag ). The message may be cited.