GCN Circular 34351

GRB 230805B: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230805B
196 s after the BAT trigger (Cenko et al., GCN Circ. 34339
Not found
 
 
).
No optical afterglow consistent with the XRT position
(Evans et al., GCN Circ. 34345
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           196          345          147         >20.2
u_FC               354          604          246         >19.5
white              196         1878          284         >20.7
v                  683         1927          135         >19.0
b                  610         1854          136         >20.4
u                  354         1829          363         >19.6
w1                 732         1804          117         >19.4
w2                1014         1730           58         >18.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.014 in the direction of the burst
(Schlegel et al. 1998).