GCN Circular 32218

N. P. M. Kuin (UCL-MSSL) and E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 220618A
151 s after the BAT trigger (Troja et al., GCN Circ. 32214
Not found
 
 
).
No optical afterglow consistent with the XRT position (Troja et al. GCN
Circ. 32214
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           151          301          147         >19.8
u_FC               309          559          246         >18.9
white              151          609          167         >19.8
v                  641          649            8         >17.4
b                  565          585           19         >17.9
u                  309          559          246         >18.9
w2                 617          637           19         >18.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.391 in the direction of the burst
(Schlegel et al. 1998).