GCN Circular 13629

P. Kuin, S. R. Oates (MSSL-UCL) and B.N. Barlow (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120811C
76 s after the BAT trigger (Barlow et al., GCN Circ. 13622
Not found
 
 
).
A source consistent with the XRT position Evans et al., GCN Circ.
13625
Not found
 
 
 is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  13:18:43.82 = 199.68258 (deg.)
    Dec (J2000) = +62:18:02.8  =  62.30077 (deg.)
with an estimated uncertainty of 0.52 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT
photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:

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

white               76          226          147         18.59 +/- 0.05
v                  620         1243           78         18.49 +/- 0.19
b                  544          739           39         18.95 +/- 0.19
u                  288          538          246         18.61 +/- 0.09
w1                 670         1464           97        >20.0
m2                 819         1439           78        >20.5
w2                 595         1219           78        >19.7

The absence of a detection in the uv bands is consistent with the reported
redshift from Thoene et al., GCN Circ. 13628
Not found
 
 
.

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).