TITLE: GCN CIRCULAR NUMBER: 17702 SUBJECT: GRB 150413A: T7 and T18 optical observations DATE: 15/04/14 14:37:36 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 150413A optical afterglow at iTelescope observatory T7 and T18 (AstroCamp Observatory, Nerpio, Spain) using T7 0.43-m/6.8 and T18 0.32-m/8.0 astrographs. The observations were started at 2015-04-13 20:29:13 (UT) and stopped at 23:54:26 (UT). Fifteen unfiltered images and four photometric R filter images with 120 sec exposure time were made. The afterglow was detected at the following position RA 21:41:41.88 and DEC +71:50:27.9. The following magnitude were obtained from the observations using USNO-B1.0 1618-0098208 (R1=14.38) as a comparison star: Telescope Tmid(h)+T0 Filter Exp. time Mag T7 6.611 unfiltered 2x120s 17.2CR T7 6.728 unfiltered 3x120s 17.4CR T7 6.976 R 2x120s 17.7R T7 7.184 R 2x120s 17.9R T18 9.508 unfiltered 4x120s 18.0CR T18 9.685 unfiltered 4x120s 18.0CR T18 9.904 unfiltered 2x120s 18.0CR --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com