NOTE: uvot_fluxes_wget.pl vrs. 2018-01-16 fem at 180829d09h28m31s717606usUT
NOTE: Source region spec. is: 268.71817 -25.79814 4"
NOTE: Used archived XRT position of 268.71817 -25.79814  4.00
NOTE: position reference is GCN_Circulars-23185

=========== Draft Upper Limit Circular ========

GRB 180828A: Swift/UVOT Upper Limits

S.W.K. Emery (UCL-MSSL) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180828A
124 s after the BAT trigger (Beardmore et al., GCN Circ. 23182).
No optical afterglow consistent with the XRT position
(LaPorte et al. GCN Circ. 23185)
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 initial exposures are:

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

white              124        23102         1416         >21.9
v                 4931        39624         1553         >20.8
b                 5752        28839         1734         >21.7
u                 5547        34577         1709         >21.2
w1                5342        33925         1968         >20.4
m2                5137        40314         1756         >20.3
w2               11215        38709         2087         >20.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 23.65 in the direction of the burst
(Schlegel et al. 1998).