TITLE:   GCN CIRCULAR
NUMBER:  42956
SUBJECT: GRB 251202A: Swift/UVOT Detection
DATE:    25/12/02 16:35:43 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 EP251202a/GRB
251202A  17,500s after the EP trigger (Zhang et al., GCN Circ. No 42937).

A source consistent with Li et al. (GCN Circ No 42934) and the XRT
position (Sbarufatti
et al. GCN Circ. No. 42943) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) = 08:08:27.5 = 122.11420 (deg.)
    Dec (J2000) = 40:36:45.3 = 40.61244 (deg.)
with an estimated uncertainty of 0.48 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

u                17500         18104         509          19.80 +/- 0.20
u                23697         24044         342         20.26 +/- 0.39
u                28710         28841         129         20.06 +/- 0.53

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.043 in the direction of the burst
(Schlegel et al. 1998).