NOTE: Possible detection in wh at T+136541.6

=========== Draft Upper Limit Circular ========

GRB 131231A: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and ***BA*** (***BA INSTITUTION***)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 131231A
136542 s after the LAT trigger (***Author*** et al., GCN Circ. ????).
No optical afterglow consistent with the optical position
(Malesani et al. GCN Circ. 15642)
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

white           136542       143352         2946         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).


=========== Draft Detection Circular ========

GRB 131231A: Swift/UVOT Detection

***UBS*** (***INSTITUTION***) and ***BA*** (***BA INSTITUTION***)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 131231A
136542 s after the LAT trigger (***Author*** et al., GCN Circ. ????).
A source consistent with the optical position
(Malesani et al. GCN Circ. 15642)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  00:42:21.65 =  10.59020 (deg.)
    Dec (J2000) = -01:39:10.7  =  -1.65298 (deg.)
with an estimated uncertainty of 0.52 arc sec. (radius, 90% confidence).

Preliminary detections 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           136762       138439         1650         19.59 +/- 0.04

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).