TITLE: GCN CIRCULAR NUMBER: 17969 SUBJECT: GRB 150626B: NOT optical upper limits DATE: 15/06/27 00:42:55 GMT FROM: Dong Xu at NAOC/CAS D. Xu (NAOC/CAS), J. Telting (NOT), J. P. U. Fynbo (DARK/NBI) report on behalf of a larger collaboration: We observed the field of GRB 150626B (McCauley et al., GCN 17966) using the 2.56m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. We obtained 2x150s SDSS r-band and 6x180s SDSS z-band frames, with their median time of 1.379 hr and 1.936 hr after the burst, respectively. No optical source is detected at the (enhanced) XRT position (McCauley et al., GCN 17966; Goad et al., GCN 17968) in our stacked r- and z-band images, down to the limiting magnitudes of r~22.3 mag and z~21.6 mag, respectively.