TITLE: GCN CIRCULAR NUMBER: 6929 SUBJECT: GRB 071013: TNT optical data refined analysis DATE: 07/10/17 15:08:04 GMT FROM: L.P. Xin at NAOC L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, J.Wang and W.K. Zheng on behalf of EAFON report: We refined the TNT data obtained in Oct. 13 (GCN 6908) the object observed by Kornienko et al. (GCN 6925) can not be confirmedin our R band images that were observed in the same period.Our data was taken under bad seeing ~4". In combined 6*60s R band image taken bewteen 12:39:03 - 12:47:54 (UT), we could not see the object at the position RA(J2000)=18:37:49.1 Dec(J2000)=+33:50:25(Kornienko et al., GCN 6925). The source of USNO-B1.0 1238-0299614(RA(J2000)=18:37:48.84 Dec(J2000)= +33:50:26.7) was marginally detected in this combined image at 2.5 sigma level, and no obvious new object around was detected at the same sigma level. We examined images before and after this period, also no obvious new object was detected. Using the same comparison star at RA (J2000) = 18:38:05.67, Dec (J2000) = +33:54:14.61 which has R2=17.22 (Kann et al., GCN 6917, GCN 6926),we estimate the USNO-B1.0 1238-0299614 star had the following magnitude at the epoch of our observation (GCN 6908): --------------------------------------------------- T_start(UT) T_stop(UT) Band Exptime Mag M_err 12:21:38 12:38:45 R 13*60s 19.3 0.3 12:39:03 12:47:54 R 6*60s 19.4 0.4 12:48:47 13:46:44 R 11*300s 19.7 0.2 --------------------------------------------------- We suggest the object reported in GCN6926 is the same star. This message may be cited.