TITLE:   GCN CIRCULAR
NUMBER:  34941
SUBJECT: GRB 231104A: Swift/UVOT Upper Limits
DATE:    23/11/04 12:44:11 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N. P. M. Kuin (UCL/MSSL) and K. L. Page (U. Leicester) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231104A
91 s after the BAT trigger (Page et al., GCN Circ. 34940).  No optical
afterglow consistent with the XRT position (Goad et al., GCN Circ. 34940)
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            91          241          147         >21.7
u_FC               304          553          246         >20.7
white               91         1709          411         >21.8
v                  633         1758          117         >19.3
b                  559         1684          117         >20.4
u                  304         1659          343         >20.9
w1                 683         1808          117         >19.7
m2                 659          679           20         >18.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.156 in the direction of the burst
(Schlegel et al. 1998).