TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4333 SUBJECT: GRB 051211A and GRB051211B: BOOTES simultaneous observations DATE: 05/12/12 07:14:03 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia M. Jelínek, A. J. Castro-Tirado, S. Vitek, A. de Ugarte Postigo (IAA-CSIC Granada), P. Kubánek and R. Hudec (Astronomical Institute of the Academy of Sciences, Ondrejov), report: The BOOTES instruments in South Spain responded to the two GRBs detected on 11 Nov 2005. The BOOTES-2 very wide field camera located at La Mayora (EELM-CSIC, Málaga) observed the region of the sky containing the HETE-2/SXC error box for GRB 051211A (Atteia et al. GCN 4324) as part of the routinary observing schedule. A 30s exposure started at 2:50:00 UT (5s prior to the beginning of the 33s long burst), i.e. overlaping with the single, hard gamma-ray peak detected by HETE-2. This image sets a R = 10 upper limit to the promt optical flash for GRB 051211A. BOOTES-1 in El Arenosillo (INTA, Huelva), responded under non-optimal conditions to the GRB 051211B trigger (Mereghetti et al. GCNC 4327). A sequence of exposures started at 22:06:34 UT (50s after the GRB onset, 30s after the GCN notice), i.e. overlaping for 30 s with the tail of the gamma-ray emission. We do no detect any transient optical emission in the 2' INTEGRAL error box and in particular at the position of the possible afterglow reported by Klotz et al. (GCNC 4328). We set a I > 14 limit to any optical emission arising simultaneusly to the gamma-rays. We also notice moderate extinction in the line of sight: E(B-V) = 0.47 from the Schlegel et al. dust maps (1998)." This message can be quoted. [GCN OPS NOTE(16dec05): Per author's request, the duplicate text was removed.]