TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4227
SUBJECT: GRB 051109a: BOOTES R & I-band detection of the early afterglow
DATE:    05/11/09 12:52:27 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>

M. Jelínek, 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."

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