GCN Circular 18597

S. R. Oates (IAA-CSIC/UCL-MSSL) and D. Malesani (DARK/NBI)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151112A
3144 s after the BAT trigger (Malesani et al., GCN Circ. 18588
Not found
 
 
).
No optical afterglow, consistent with the enhanced XRT position
(Osborne et al. GCN Circ. 18592
Not found
 
 
) and the GROND position 
(Knust et al., GCN Circ. 18595
Not found
 
 
), is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

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

white_FC          3144         3294          147         >21.3
white             3144         4527          344         >21.8
v                 3301         4938          393         >20.2
b                 4123        10985          349         >21.1
u                 3917        10825         1082         >21.5
w1                3711         9912         1169         >21.4
m2                3506        15760         1240         >21.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).