GCN Circular 17892

M. De Pasquale (UCL-MSSL) and R. L. C. Starling (U Leicester)report on 
behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150530A 
106 s after the BAT trigger (Starling et al., GCN Circ. 17888
Not found
 
 
).
No optical afterglow consistent with the XRT position (Goad et al.
GCN Circ. 17889
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           106          256          147 >20.1
u_FC               319          562          238 >19.2
white              106         5690          541 >21.0
v                 4465         6101          393 >19.3
b                 3849         5485          393 >20.4
u                  319         5280          435 >19.7
w1                4875         5075          197 >19.5
m2                4670         6306          393 >19.9
w2                4260         5896          393 >20.1

The magnitudes in the table are not corrected for the strong Galactic
extinction due to the reddening of E(B-V) = 1.81 in the direction of
the burst (Schlegel et al. 1998).