TITLE: GCN CIRCULAR NUMBER: 18878 SUBJECT: GRB 160117B: LCOGT-SSO optical observations DATE: 16/01/17 15:55:37 GMT FROM: Thomas Kruehler at MPE Garching T. Kruehler (MPE), D. Xu (NAOC/CAS), Y.-D. Hu (IAA-CSIC), Y. Qing (Geneva Observatory), Y.-H. Han (NAOC/CAS, HUST) report: We observed the field of GRB 160117B (Swift trigger 670793, Sonbas et al., GCN 18875) using the LCOGT-1m located at the Siding Spring Observatory. Observations started at 14:20:45 UT on 2016-01-17 (i.e., 1278 s after the burst), and a series of 180 s R-band images have been obtained. Further observations are ongoing. The optical afterglow is detected at coordinates: R.A. (J2000) = 08:48:46.74 Dec. (J2000) = -16:22:00.0 with an error radius of 0.2 arcsec, which is fully consistent with the UVOT position from GCN 18875. The afterglow has R = 18.3 +- 0.1 mag from the first 180 s exposure, calibrated with the nearby USNO B1 stars (R1 magnitudes). The afterglow has been decaying rather slowly, with a decay slope of -0.5 +- 0.1 so far.