TITLE: GCN CIRCULAR NUMBER: 18083 SUBJECT: GRB 150727A: LCOGT-Cerro Tololo observations DATE: 15/07/28 10:03:02 GMT FROM: Simone Dichiara at Ferrara U/Italy S. Dichiara, C. Guidorzi (U. Ferrara), C.G. Mundell (U. Bath), S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana) on behalf of a large collaboration report: Using a 1-m LCOGTN telescope in Cerro Tololo (Chile), we began observing GRB 150727A (Cenko et al. GCN 18076; Younes et al. GCN 18081) on July 28 01:23:01 UT (~6.3 hours after the burst trigger) with r' and i' filters. We did not detect the UVOT counterpart (Cenko et al. 2015, GCN 18076) down to the following limit: Mid time from Total Exp Filter Magnitude trigger (hr) (s) ------------------------------------------------- 6.71 120x10 r' > 18.9 6.76 120x9 i' > 16.5 ------------------------------------------------- Values have been calibrated against nearby USNOB-1 stars (R2 and I).