GCN Circular 4227
M. Jel�nek, A. de Ugarte Postigo, A. J. Castro-Tirado, S. Vitek, J. Gorosabel, S. B. Pandey and S. S. Guziy (IAA-CSIC Granada), P. Kubanek (ISDC Versoix, and ASU AV CR Ondrejov) and R. Hudec (ASU AV CR) report: "BOOTES-1B in El Arenosillo (southern Spain), responded to the GRB 051109a trigger (Tagliaferri et al. GCNC 4213). A sequence of exposures started at 01:13:15.3 UT (54.8s after the GRB, 27s after the GCN notice), simultaneously in the R and I-bands. We detect the optical afterglow first reported by Rykoff et al. (GCNC 4211) in both passbands. The approximate magnitude on the first 10s R-band image is 16.2 calibrated against USNO-A2.0. Further analysis is in progress." This message may be cited.