TITLE:   GCN CIRCULAR
NUMBER:  42954
SUBJECT: GRB 251201B: Swift/UVOT Detection
DATE:    25/12/02 15:52:28 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

N.P.M. Kuin  (UCL-MSSL) and M. J. Moss (GSFC) report on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 251201B  101
s after the BAT trigger (Moss et al., GCN Circ. 42924).  A source
consistent with the XRT position is detected in the initial UVOT exposures.

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              101          251          147         17.31 +/- 0.03
v                  644          663           19         15.97 +/- 0.12
b                  570          589           20         16.71 +/- 0.10
u                  314          564          246         16.48 +/- 0.04
w1                 693         1808          117         18.35 +/- 0.18
m2                 668         1093           39        >18.7
w2                1196         1562           39        >18.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.008 in the direction of the burst
(Schlegel et al. 1998).