TITLE:   GCN CIRCULAR
NUMBER:  42353
SUBJECT: GRB 251018A: Swift/UVOT Detection
DATE:    25/10/18 11:57:31 GMT
FROM:    Paul Kuin at MSSL <npkuin@gmail.com>

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

The Swift/UVOT began settled observations of the field of GRB 251018A 84 s
after the BAT trigger (Gupta et al., GCN Circ. 42343).  A source consistent
with the XRT position is detected in the initial UVOT exposures.

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               84          128           44         17.98 +/- 0.08

The magnitudes in the table are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.101 in the direction of the burst (Schlegel
et al. 1998).