TITLE: GCN CIRCULAR NUMBER: 14426 SUBJECT: GRB 130420B: Weihai optical upper limit DATE: 13/04/20 22:06:40 GMT FROM: Dong Xu at DARK/NBI Dong Xu (DARK/NBI), Chen Cao, Shaoming Hu, Dayong Ren (SDU) report: We observed the field of GRB 130420B (Oates et al., GCN 14411) using the 1m telescope located in Weihai, Shandong Province, China. We obtained 12x300s I-band frames with a mean time of 2.973 hr after the BAT trigger. No optical source is detected within the enhanced XRT error circle (Page et al., GCN 14421) in the stacked image, down to a limiting magnitude of I>21.2 mag.