TITLE: GCN CIRCULAR NUMBER: 6250 SUBJECT: GRB 070406: Xinglong TNT optical Upper Limit DATE: 07/04/07 00:38:13 GMT FROM: L.P. Xin at NAOC W.K. Zheng, M.Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, Y. Urata, J.Z. Li and L.P. Xin on behalf of EAFON report: We have imaged the field of GRB 070406 with the TNT 0.8m telescope at Xinglong Observatory started from 20:42:33 UT on Apil. 6, about 19.86 hours after the burst. seven white band images were obtained, and no new source was found in our Totally combined image within the error region of BAT of the Swift. the 3-sigma limit is ~19.8 derieved form USNO A-2.0. This message may be cited.