GCN Circular 20441

M.H. Siegel (PSU) and A. P. Beardmore (U Leicester) 
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170111A
111 s after the BAT trigger (Beardmore et al., GCN Circ. 20423
Not found
 
 
).
No optical afterglow consistent with the XRT position
(Evans et al., GCN Circ. 20424
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           111          261          147         >20.6
white              111          570          167         >20.7
v                  601          621           19         >18.0
b                  525          545           19         >19.6
u                  676          696           19         >19.3

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).