GCN Circular 22779

S. Sebzda (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180613A
156 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 22769
Not found
 
 
).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 22773
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

u_FC               156          405          246         >20.4
v                  461        24234         1434         >20.9
b                  411        13230         1022         >99.0
u                  156        18973         2109         >21.8
w1                 510        18472         2212         >21.2
m2                 486        24474         1627         >21.0
w2                1036        23321         1318         >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.09 in the direction of the burst
(Schlegel et al. 1998).