TITLE: GCN CIRCULAR NUMBER: 15916 SUBJECT: GRB 140304A: Afterglow decay from Nanshan observations DATE: 14/03/04 14:26:19 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), H.-B. Niu, G.-J. Feng, T.-Z. Yang, A. Esamdin, L. Ma (XAO) report: We observed the field of GRB 140304A (Evans et al., GCN 15915) using the 1m telescope located in Nanshan, Xinjiang, China. Observations started at 13:43:26 UT on 2014-03-04 (i.e., 0.349 hr after the BAT trigger) and a series of 120s and 500s R-band images were obtained. In the first 120s R-band image, an optical source is clearly detected at the MASTER position (Gorbovskoy et al., GCN 15914), which is also consistent with the Swift/XRT position. We thus think this is the afterglow of the burst, and it has decayed to R=19.4+/-0.2 mag, calibrated with nearby SDSS stars. Observations are ongoing.