TITLE: GCN CIRCULAR NUMBER: 14110 SUBJECT: GRB 121226A: NOT optical upper limit DATE: 12/12/27 07:46:12 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), O. Smirnova, T. Purismo (NOT), J. P. U. Fynbo (DARK/NBI), P. Jakobsson (U. Iceland) report on behalf of a larger collaboration: We observed the field of GRB 121226A (Krimm et al., GCN 14105) using the 2.5m Nordic Optical Telescope (NOT) equipped with ALFOSC. We obtained 3x600s R-band and 3x360s z-band images with their median time of 06:14:49 UT on 2012-12-27 (i.e., 11.085 hr after the BAT trigger) and 06:53:54 UT (i.e., 11.736 hr post-trigger), respectively. No optical source was detected within the XRT error circle in both R-and z-bands, down to a 3sigma limit of R~23.0 mag ,calibrated with the USNO B1 catalogue.