GCN Circular 33266

S. J. LaPorte (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230204A
156 s after the BAT trigger (D'Ai et al., GCN Circ. 33260
Not found
 
 
).
No optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 33261
Not found
 
 
)
is detected in the initial UVOT exposures.
A known source with no significant signs of fading
is detected 2.88 arcsec from the XRT position at:

RA (J2000): 15h 52m 47.83s
Dec (J2000): -50d 54' 56.74"

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           156            306          147          >17.5
u_FC                  314            564          246         >19.1
white                  156          1372          373         >17.8
v                         645          1596          117         >15.9
b                         570          1521            97         >17.9
u                         314          5553          382         >19.1
w1                      695           5489          274         >19.1
m2                      670          1446            97         >18.8
w2                       621          1571          117         >18.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 2.516 in the direction of the burst
(Schlegel et al. 1998).