TITLE: GCN CIRCULAR NUMBER: 17835 SUBJECT: GRB 150518A : Xinglong TNT upper limit DATE: 15/05/21 04:01:03 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 150518A (Kawamuro, et al., GCN 17825) with Xinglong 0.8-m TNT telescope during 2015-05-20, 16:51:46 and 18:16:34 (UT), bout 43.2-44.7 hour after the trigger time. No any source was detected in our 17*300sec R-band coadded image within the Swift-XRT error circle (Sbarufattim et al., GCN 17827) and at the location of the reported source (Xu et al., GCN 17829; Mao et al., GCN 17830) down to the 3 sigma limit of 20.7 mag, calibrated by USNO B1.0 R2 mag.