TITLE: GCN CIRCULAR NUMBER: 20998 SUBJECT: GRB 170405A: Etelman observatory optical observations DATE: 17/04/06 19:41:45 GMT FROM: Bruce Gendre at UVI B. Gendre (UVI), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (UVI), A. Cucchiara (UVI), D. Drost (UVI), T. Giblin (USAF Academy), J. Hakkila (College of Charleston), A. Klotz (IRAP), J. Neff (NSF), D. Smith (UVI), J. Staff (UVI), P. Thierry (Auragne Observatory), R. Watlington (UVI), and L. Wentlent (UVI) report: We observed the field of GRB 170405A (Troja et al, GCN 20984; Hui & Meegan, GCN 20986; Vianello & Kocevski, GCN 20987) with the 0.5m Virgin Island Robotic Telescope (VIRT) on February the 6th, starting at 6:15 UT (11.6 hours after the trigger). We performed a series of exposures in the clear filter. The weather conditions were good during the observations. We co-added the exposures taken between 6h15UT (t0+11.6h) and 7h29UT (t0+12.8h), for a total exposure of 3510s. At the position of the optical afterglow reported by Malesani et al. (GCN 20988), we do not detect any optical emission, with an upper limit of R = 21.3 (Johnson system) estimated from nearby NOMAD1 stars. Magnitudes have not been corrected for Galactic extinction. The VIRT is still in its commissioning phase. This message can be cited.