TITLE:   GCN CIRCULAR
NUMBER:  17400
SUBJECT: GRB 150203A:  Swift/UVOT Upper Limits
DATE:    15/02/04 13:38:23 GMT
FROM:    Margaret Chester at PSU  <chester@swift.psu.edu>

M. M. Chester (PSU) and T. N. Ukwatta (LANL) report on behalf of the 
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150203A
83 s after the BAT trigger (Ukwatta et al., GCN Circ. 17377).
No optical afterglow consistent with the enhanced XRT position 
(Evans et al. GCN Circ. 17384) 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) exposures and subsequent exposures are:

Filter   T_start(s)   T_stop(s)      Exp(s)       Mag

white_FC         83         232         147     >20.6
white            83        1197         353     >21.2 
v               624        1246          78     >18.7
b               550        1172          58     >19.4
u_FC            295         545         246     >20.0
u               295        1148         285     >20.0
w1              674        1278          61     >18.8
m2              649        1271          78     >18.7
w2              600        1222          78     >19.0

The magnitudes in the table are not corrected for the large Galactic 
extinction in the direction of the burst (reddening of E(B-V) = 0.9; 
Schlegel et al. 1998).