TITLE: GCN CIRCULAR NUMBER: 16326 SUBJECT: GRB 140523A: Nanshan optical upper limit DATE: 14/05/24 15:43:48 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), C.-H. Bai, J. Xu, A. Esamdin, L. Ma (XAO) report: We observed the field of the possible XRT afterglow (D'Elia et al., GCN 16324) of GRB 140523A (von Kienlin et al., GCN 16321; Vianello et al., GCN 16322) using the 1m telescope located at Nanshan, Xinjiang, China. Observations started at 15:06:12 UT on 2014-05-24 (i.e., 36.0 hr after the burst), and 2x180s and 2x600s R-band frames were obtained. No optical source is detected at the XRT position down to a limiting magnitude of R=20.5, calibrated with the SDSS field.