GCN Circular 13448

A. A. Breeveld (MSSL-UCL) and M. J. Page (MSSL-UCL) report on behalf of 
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120711A
8216 s after the INTEGRAL trigger (Gotz et al., GCN Circ. 13434
Not found
 
 
).
No significant optical afterglow consistent with the position given in 
Lacluyze et al. (GCN_Circ. 13430) is detected in the initial UVOT 
exposures. However, in the U filter, the source may be detected at this 
position with a significance of 2 sigma. The possible detection is 
included in the table.
Preliminary 3-sigma upper limits using the UVOT photometric system 
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial 
exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

b                 8464         8480           16         >18.7
u                 8380         8459           79         >19.4
w1                8216         8375          157         >19.8

u                 8380         8459           79        19.6 � 0.5 (2sig)


The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.08 in the direction of the 
burst (Schlegel et al. 1998).