GCN Circular 19134

S.W.K. Emery (UCL-MSSL) 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 160303A
109 s after the BAT trigger (Beardmore et al., GCN Circ. 19126
Not found
 
 
).
We detect a fading source consistent with the XRT position
(Beardmore et al. GCN Circ. 19126
Not found
 
 
) and the RATIR optical and NIR afterglow
detections (Butler et al. GCN Circ 19131)
in the initial UVOT u filter 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           109         259          147         >21.9
u_FC                   321         571          246          20.75
white                 109          2061        450         >22.5
b                         576          2037        136         >19.9
w1                      700          2161           77         >20.5
m2                     1426        1445           19         >19.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).