TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3431 SUBJECT: GRB 050520: BART optical limit DATE: 05/05/20 01:37:11 GMT FROM: Martin Jelinek at Inst.Astrophys.Andalucia,Granada Martin Jelinek (IAA Granada, Spain), Martin Nekola, Petr Kubanek, Filip Munz, Jan Strobl and Rene Hudec (ASU AV CR Ondrejov, Czech Republic) report: Robotic telescope BART located at Astronomical Institute in Ondrejov has observed the errorbox of the INTEGRAL trigger 2505 15 minutes after the GRB time. We do not detect any new source within the given errorbox down to limiting magnitude V=14.