TITLE:   GCN CIRCULAR
NUMBER:  15621
SUBJECT: GRB 131227A: Swift/UVOT Upper Limits
DATE:    13/12/27 15:55:33 GMT
FROM:    Massimiliano de Pasquale at MSSL-UCL  <m.depasquale@ucl.ac.uk>

M. De Pasquale (UCL-MSSL) and S. R. Oates (UCL-MSSL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 131227A
66 s after the BAT trigger (Oates et al. GCN Circ. 15616).
No optical afterglow consistent with the enhanced XRT position
(Evans et al. GCN Circ. 15618) or the source detected by KAIT (Zheng
et al. GCN 15617) 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            66          216          147         >20.6
u_FC               278          528          246         >19.9
white               66        13019         1430         >21.9
v                  608         6785          471         >19.7
b                  534        12318         1160         >21.1
u                  278        11406         1366         >20.9
w1                5558         7195          393         >20.1
w2                4942         6580          393         >20.5

The magnitudes in the table are not corrected for the strong Galactic
extinction due to the reddening of E(B-V) = 1.02 in the direction of
the burst (Schlegel et al. 1998).