TITLE:   GCN CIRCULAR
NUMBER:  12783
SUBJECT: GRB 111229A: Swift/UVOT Detection
DATE:    11/12/30 13:32:12 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (MSSL-UCL) and A. Y. Lien (NASA/GSFC/ORAU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 111229A
87 s after the BAT trigger (Lien et al., GCN Circ. 12774).
A source consistent with the XRT position (Osborne et al., GCN Circ. 12780) and 
the GROND optical position (Nicuesa Guelbenzu et al., GCN Circ. 12780) is 
detected in the initial UVOT exposures.

The preliminary UVOT position is:
  RA  (J2000) =  05:05:08.86 =  76.28692 (deg.)
  Dec (J2000) = -84:42:39.1  = -84.71085 (deg.)
with an estimated uncertainty of 0.55 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white (FC)        87            237           147          18.78 +/- 0.10
white            5230          5430           200          20.48 +/- 0.27
v                      630            649              20          17.70 +/- 0.49
b                     554             574             20          18.75 +/- 0.53
u (FC)            300             549           250          19.03 +/- 0.23
u                   4820          5020           200	      20.67 +/- 0.53
w1                  679           6251          413           >20.4
m2               4410           6046          393           >20.4
w2                  779        22585        1597           >21.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.18 in the direction of the burst
(Schlegel et al. 1998).