TITLE:   GCN CIRCULAR
NUMBER:  23419
SUBJECT: GRB 181110A: Swift/UVOT Detection
DATE:    18/11/10 21:56:35 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181110A
72 s after the BAT trigger (Evans et al., GCN Circ. 23413).
The GRB was detected in ground photometry (Yamanaka et al., GCN
Circ. 23414; Murata et al., GCN Circ. 23415; Denisenko et al.
GCN Circ. 23416).  The UVOT detects a source consistent
with the XRT position (Goad et al. GCN Circ. 23417) in the initial
UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  20:09:16.27 = 302.31781 (deg.)
    Dec (J2000) = -36:53:47.9  = -36.89664 (deg.)
with an estimated uncertainty of 0.46 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               72          222          147         18.52 +/- 0.07
v                  614          634           19         16.09 +/- 0.13
b                  540          559           20         16.98 +/- 0.11
u                  284          534          246         16.66 +/- 0.04
w1                 663          683           19         15.65 +/- 0.13
m2                1068         1088           20         14.66 +/- 0.11
w2                1018         1038           20         15.74 +/- 0.14

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.07 in the direction of the burst
(Schlegel et al. 1998).

The source showed a rebrightening with a late peak at around 1100s after
the trigger.