TITLE:   GCN CIRCULAR
NUMBER:  33370
SUBJECT: GRB 230217A: Swift/UVOT Upper Limits
DATE:    23/02/22 21:02:57 GMT
FROM:    Alexander Belles at PSU/Swift  <aub1461@psu.edu>

The Swift/UVOT began settled observations of the field of GRB 230217A
45.8 ks after the Swift/BAT trigger (Moss et al., GCN Circ. 33339).
No optical afterglow consistent with the XRT position
(Capalbi et al., GCN Circ. 33365) 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 initial exposures are:

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

wh               45886        84347         2643        >21.37
u               329962       342875         4884        >20.78

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.15 in the direction of the burst
(Schlegel et al. 1998).