TITLE:   GCN CIRCULAR
NUMBER:  17892
SUBJECT: GRB 150530A: Swift/UVOT Upper Limits
DATE:    15/05/30 21:29:27 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

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).
No optical afterglow consistent with the XRT position (Goad et al.
GCN Circ. 17889) 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).