TITLE:   GCN CIRCULAR
NUMBER:  35475
SUBJECT: GRB 240102A: Swift/UVOT Upper Limits
DATE:    24/01/03 15:38:51 GMT
FROM:    Alexander Belles at PSU <aub1461@psu.edu>

A. Belles (PSU) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 240102A
113 s after the BAT trigger (Gropp et al., GCN Circ. 35461).
No optical afterglow consistent with the XRT position
(Goad et al., GCN Circ. 35471) 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           135          285          147         >20.7
u_FC               294          544          246         >19.9
white              135         1196          353         >21.1
v                  113         1246           90         >18.8
b                  550         1172           58         >19.5
u                  294         1314          299         >20.0
w1                 676         1295           78         >19.0
m2                 823         1270           58         >18.7
w2                 600         1221           78         >19.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.176 in the direction of the burst
(Schlegel et al. 1998).