NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 230228d23h00m13s468078usUT
NOTE: Source region spec. is: 18.37813 44.48292 4"
NOTE: Used archived XRT position of  18.37813  44.48292  4.00
NOTE: position reference is GCN_Circulars-33382

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

GRB 230228A: Swift/UVOT Upper Limits

A. A. Breeveld (UCL-MSSL) and S. Dichiara (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230228A
122 s after the BAT trigger (Dichiara et al., GCN Circ. 33378).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 33382)
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           122          272          147         >20.1
u_FC               335          585          246         >19.5
white              122         1705          411         >20.9
v                  665         1756          136         >18.8
b                  590         1854          134         >20.4
u                  335         1830          363         >19.7
w1                 714         1806          117         >20.0
m2                 689         1780          117         >19.7
w2                 640         1731          136         >21.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.085 in the direction of the burst
(Schlegel et al. 1998).