TITLE: GCN CIRCULAR NUMBER: 19409 SUBJECT: GRB 160509A: optical observations DATE: 16/05/09 16:52:26 GMT FROM: Luca Izzo at IAA-CSIC L.Izzo (IAA-CSIC), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), C. Thoene (IAA-CSIC) report: We observed the field of GRB 160509A (Longo et al., GCN 19403; Ono et al., GCN 19404) with the iTelescope.Net ( http://www.itelescope.net) T11 (Planewave CDK 0.51m) telescope located at the Mayhill observatory (NM). A single image of 300 s was obtained in the R filter, starting at 10:32:32 UT, 1.56 hr after the GRB trigger. We do not detect any optical afterglow candidate at the refined Swift-XRT position (Kennea et al. GCN 19408). We estimate an upper limit magnitude of R = 19.5 mag (3-sigma), using the USNO-B1 catalog as reference. We note that our image covers also the complete error box of the MAXI (Ono et al., GCN 19404). Data are available on request. An image of the field of view can be seen at http://goo.gl/dKTki3 [GCN OPS NOTE(09may16): Per author's request, The affiiation and reply-to email address of LI was changed.]