TITLE:   GCN CIRCULAR
NUMBER:  15036
SUBJECT: GRB 130725A: Swift/UVOT Upper Limits
DATE:    13/07/26 11:49:46 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (UCL-MSSL) and B.-B. Zhang (PUS/UAH)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130725A 
(Zhang et al., GCN Circ. 15028) 3097 s after the BAT trigger (trigger=563980).
No optical afterglow consistent with the XRT position 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          3097         3247          147         >21.1
white             3097         4480          344         >21.0
v                 3255        10746         1278         >20.4
b                 4075         5690          373         >20.4
u                 3870        17226         1118         >21.0
w1                3665        16476         1279         >21.0
m2                3460        11458         1089         >21.0
w2                4486         9832         1082         >21.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).