TITLE: GCN CIRCULAR NUMBER: 21113 SUBJECT: GRB 170519A: iTelescope T11 optical observations DATE: 17/05/19 15:42:57 GMT FROM: Veli-Pekka Hentunen at Taurus Hill Obs,A95 Veli-Pekka Hentunen and Markku Nissinen (Taurus Hill Observatory (A95), Varkaus, Finland) report: We have detected GRB 170519A optical afterglow at iTelescope observatory T11 (Mayhill, New Mexico) using 0.51-m/6.8 Planewave CDK telescope and FLI ProLine PL11002M CCD camera. The observations were started at 2017-05-19 05:25:24 (UT). Eleven unfiltered images and seven photometric R filter images with 120 sec exposure time were taken. The optical afterglow was detected at the position RA 10:53:42.46 and DEC +25:22:27.4. The following magnitudes were obtained from the observations using NOMAD1 1153-0183949 (R = 12.650) as a comparison star: Tmid(s)+T0 Filter Exp. time Mag Mag err. 1119 unfiltered 3x120 15.52CR 0.03 1452 unfiltered 2x120 15.63CR 0.03 1906 R 3x120 15.98R 0.10 2324 R 2x120 16.08R 0.11 2806 unfiltered 4x120 16.07CR 0.05 3327 unfiltered 2x120 16.17CR 0.05 3795 R 2x120 16.50R 0.16 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus