TITLE:   GCN CIRCULAR
NUMBER:  35308
SUBJECT: GRB231205B: Swift/UVOT Upper Limits
DATE:    23/12/08 17:38:53 GMT
FROM:    Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>

M. H. Siegel (PSU) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231205B
216 s after the BAT trigger (Evans et al., GCN Circ. 35269).
No optical afterglow consistent with the XRT position
(Osborne et al. 35275) 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           237          387          147         >21.3
white              237          536          167         >21.3
v                  216          414           33         >18.6
b                  492          512           19         >19.6
u                  468          487           19         >18.2
w1                 443          463           19         >19.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.204 in the direction of the burst
(Schlegel et al. 1998).