TITLE:   GCN CIRCULAR
NUMBER:  22239
SUBJECT: GRB 171211A: Swift/UVOT Upper Limits
DATE:    17/12/11 17:01:01 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 171211A
362 s after the BAT trigger (Gropp et al., GCN Circ. 22234).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 22236)
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

v                    387         6321          491         >19.0
uvw1                 436         6731          491         >19.7
uvm2                5503         6526          393         >19.9
uvw2                 362         6939          668         >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.11 in the direction of the burst
(Schlegel et al. 1998).