TITLE: GCN CIRCULAR NUMBER: 19960 SUBJECT: GRB 160927A: NOT optical observations DATE: 16/09/28 05:44:46 GMT FROM: Dong Xu at NAOC/CAS D. Xu (NAOC/CAS), D. Malesani (DARK/NBI and DTU Space), H. Dahle, B. Racine (Oslo U.), T. Pursimo (NOT), J. P. U. Fynbo (DARK/NBI), report on behalf of a larger collaboration: We observed the field of GRB 160927A (Gibson et al., GCN 19952) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 21:24:39 UT on 2016-09-27 (i.e., 3.33 hr after the trigger) and 5x300s SDSS r-band frames were obtained. The previously reported optical afterglow of the burst (Tkachenko et al., GCN 19954; D'Avanzo et al., GCN 19956; Wiseman et al., GCN 19959) is clearly detected in our stacked r-band image. It has m(r)=23.07 +/- 0.10 at a median time of 3.56 hr post-burst, calibrated with nearby SDSS stars. Combined with the RTT150, TNG, and GROND data points reported in the above GCN Circulars, we confirm the steepening of the afterglow light-curve (Wiseman et al., GCN 19959). A rough estimate gives rise to alpha_1~0.6, a break time of ~3.1 hr post-burst, and alpha_2~1.7 (but poorly constrained).