TITLE:   GCN CIRCULAR
NUMBER:  13948
SUBJECT: GRB 121102A: Swift/UVOT Upper Limits
DATE:    12/11/02 18:48:01 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (MSSL-UCL) and V. D'Elia (ASDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 121102A
58 s after the BAT trigger (D'Elia et al., GCN Circ. 13938).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 13945) 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            58          207          147         >20.1
u_FC               270          519          246         >19.6
white               58        24618         2113         >21.4
v                 4994        17253         1278         >20.0
b                 5814        23858         2022         >21.4
u                  270        22945         1524         >20.9
w1                5404        18848         1066         >20.8
m2                5200        18158         1279         >21.1
w2                4789        13077         1073         >21.2

The magnitudes in the table are not corrected for the high Galactic extinction
due to the reddening of E(B-V) = 1.48 in the direction of the burst
(Schlegel et al. 1998).