TITLE: GCN CIRCULAR NUMBER: 10643 SUBJECT: GRB 100418A: RTT150 optical observations DATE: 10/04/21 15:06:43 GMT FROM: Irek Khamitov at TUG I. Bikmaev (KSU/AST), I. Khamitov (TUG), S. Melnikov, N. Sakhibullin (KSU/AST), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.) report: The optical afterglow of GRB 100418A (Marshall et al., GCN 10612, Filgas et al., GCN 10617) was observed with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey) in April 20/21, 2010, at moderate seeing conditions. We obtained a serie of 600 sec and 300 sec images in Rc-band. The Table gives our Rc value estimation relative nearby USNO-B1.0 star 1014-0271368 (R2Mag=17.32). April 21, 2010 UT (T-T0), h Rc err ================================= 00:48 51.6 20.05 +/-0.03 -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.