GCN Circular 35134

N.P.M. Kuin (MSSL/UCL) and S. L. Laha (GSFC/UMBC) report

on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231117A
106 s after the BAT trigger (Laha et al., GCN Circ. 35071
Not found
 
 
).
A source consistent with the XRT position (Beardmore et al.,
GCN Circ. 35074
Not found
 
 
  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              106         1713          392         21.21 +/- 0.27
v                  648         1418           78        >18.8
b                  574         1688           78        >19.3
u                  318          741          265        >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.071 in the direction of the burst
(Schlegel et al. 1998).