TITLE:   GCN CIRCULAR
NUMBER:  35777
SUBJECT: GRB 240222A: Swift/UVOT Upper Limits
DATE:    24/02/22 22:34:59 GMT
FROM:    Samantha Oates at University of Birmingham <samantha.oates@alumni.ucl.ac.uk>

S. R. Oates (Lancaster. U) and P. D'Avanzo (INAF-OAB) report on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 240222A
98s after the BAT trigger (D'Avanzo et al., GCN Circ 35770). No optical
afterglow consistent with X-ray (D'Avanzo et al., GCN Circ. 35770) position 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

white          98            1192          205            >20.9
v              642           1068           58            >18.5
b              567           1168           58            >19.5
u              311           1142          285            >20.0
uvw1           691           1118           39            >18.3
uvm2           666           861            39            >18.0
uvw2           617           1044           58            >18.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.16 in the direction of the burst
(Schlegel et al. 1998).