TITLE: GCN CIRCULAR NUMBER: 18960 SUBJECT: GRB 160131A: iTelescope optical observations DATE: 16/01/31 19:52:46 GMT FROM: Veli-Pekka Hentunen at Taurus Hill Obs,A95 Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report: We have detected GRB 160131A optical afterglow at iTelescope observatory (Siding Spring, Australia) using T9 0.32-m f/9 RCOS telescope and T17 and T32 0.43-m f/6.8 astrographs. The observations were started at 2016-01-31 10:01:17 (UT). Several images using photometric R and V filters with 300 sec and 120 sec exposure time were taken. The afterglow was detected at the position RA 05:12:40.34 and DEC -07:02:58.3. The following magnitudes were obtained from the observations using NOMAD1 0829-0078536 (R=15.390 and V=14.820) as a comparison star: T32 observations Tmid(s)+T0 Filter Exp. time Mag Mag. Err. 6197 V 300s 15.05 0.04 6796 V 300s 15.17 0.04 7395 V 300s 15.28 0.04 T17 observations Tmid(s)+T0 Filter Exp. time Mag Mag. Err. 6651 R 4x300s 15.71 0.02 7946 R 4x300s 15.96 0.02 11649 R 4x300s 16.56 0.03 12952 R 4x300s 16.68 0.03 14244 R 4x300s 16.86 0.04 15709 R 4x300s 16.99 0.04 T9 observations Tmid(s)+T0 Filter Exp. time Mag Mag. Err. 14761 V 5x120s 16.27 0.34 15454 V 5x120s 16.43 0.37 16190 V 5x120s 16.55 0.42 17083 V 5x120s 16.55 0.44 17767 V 5x120s 16.59 0.43 18452 V 5x120s 16.65 0.48 19179 V 5x120s 16.70 0.54 20295 V 5x120s 16.75 0.56 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus