TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4251
SUBJECT: GRB 051111: ROTSE-III Analysis of Prompt Counterpart
DATE:    05/11/11 07:01:36 GMT
FROM:    Eli Rykoff at U of Michigan/ROTSE  <erykoff@umich.edu>

E.S. Rykoff (U Mich), W. Rujopakarn (U Mich), H. Swan (U Mich), B. 
Schaefer (Louisiana State), S.A. Yost (U Mich), R. Quimby (U Texas), 
report on behalf of the ROTSE collaboration:

A fast fading optical transient has been discovered inside the error 
circle for GRB 051111A (Swift trigger 163438, Sakamoto et al, GCN 4248) 
by the ROTSE-IIIb telescope, located at McDonald Observatory (see 
Rujopakarn et al, GCN 4247). The initial response was during the BAT 
emission, when the transient was at 13.0 mag (unfiltered, relative to 
USNO A2.0). The transient faded as a simple power law with decay index ~ 
-0.9. At UT 06:41:57 (t+2500s), the transient was at 17.4 mag.

Continuing observations are in progress.