GCN Circular 17538

M. M. Chester (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150302A
110 s after the BAT trigger (Lien et al., GCN Circ. 17526
Not found
 
 
). No optical 
afterglow consistent with the optical candidate reported by Fynbo et al. 
(GCN Circ. 17527
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) are as follows.  We report only the 
second finding chart (FC) exposure and subsequent exposures; the first 
finding chart exposure was too short (< 2 s) to be useful.

Filter         T_start(s)   T_stop(s)      Exp(s)        UL (3-sigma)

white_FC        3436         3585          147         >21.4
white           3436        11616          993         >22.1
v               5262        28248         1077         >21.0
b               3799        17368         1738         >22.2
u               3594        23030         2557         >21.9
w1              5672        22421         1960         >21.5
m2              5466        28871         1690         >22.4
w2              4210        27342          995         >21.4

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).