GCN Circular 17882

A. A. Breeveld (UCL-MSSL) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150527A 68 
s after the BAT trigger (Evans et al., GCN Circ. 17874
Not found
 
 
).
No optical afterglow consistent with the enhanced XRT position (Evans et 
al. GCN Circ. 17879
Not found
 
 
) or with the RATIR or REM sources (Butler et al., 
GCN Circ. 17876
Not found
 
 
 and Nicastro et al., GCN Circ. 17881
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            68          218          147         >20.2
u_FC               280          523          240         >19.1
white            10385        11927         1542         >21.2
v                 4315         4515          197         >18.8
b                 3700        10380         1082         >20.8
u                  280         6271          623         >19.6
w1                5920         6120          197         >19.4
w2                4110        12019          281         >19.8

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.97 in the direction of the 
burst (Schlegel et al. 1998). We note however that the value for 
extinction could be unreliable at this position.