GCN Circular 23581

GRB 181228A: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and M. J. Moss (George Washington University)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181228A
93 s after the BAT trigger (Moss et al., GCN Circ. 23570
Not found
 
 
).
No optical afterglow consistent with the XRT position
(Moss et al. GCN Circ. 23570
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) for the first
finding chart (FC) exposure and subsequent exposures are:

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

white_FC            93          243          147         >20.4
u_FC               305          555          246         >20.6
white               93         1354          373         >21.0
v                  634         1404           97         >19.1
b                  561         1330           78         >20.5
u                  305         1305          304         >20.5
w1                 684         1280           39         >18.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.51 in the direction of the burst
(Schlegel et al. 1998).