TITLE: GCN CIRCULAR NUMBER: 46248 SUBJECT: GRB 261113A: JinShan optical afterglow detection DATE: 26/11/13 15:57:38 GMT FROM: liuxing@nao.cas.cn L. Lei (HUST), X. Liu, D. Xu, J. An, L.B. He, S.Q. Jiang, Z.P. Zhu (NAOC), A.D. Zhu (HUST) report: We observed the field of GRB 261113A detected by SVOM/ECLAIRs (GCN 46244) using the 100A and 100C telescopes of the JinShan project locate at Altay, Xinjiang, China. A series of Sloan r-band frames were obtained. An uncatalogued and varying optical source is detected within the SVOM/ECLAIRs error circle at coordinates R.A. (J2000) = 23:05:16.96 Dec. (J2000) = +5:10:18.65 with an uncertainty of ~1 arcsec. The source has r = 19.14 +/- 0.05 mag at a median time of 0.5 hr post-trigger, calibrated with nearby PanSTARRS stars. We thus think the source is the optical afterglow of GRB 261113A.