TITLE:   GCN CIRCULAR
NUMBER:  22922
SUBJECT: GRB 180706A: Swift/UVOT Detection
DATE:    18/07/06 18:42:37 GMT
FROM:    Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>

S. R. Oates (U.Warwick) and M. Stamatikos (OSU/NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180706A
95 s after the BAT trigger (Stamatikos et al., GCN Circ. 22909).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 22916) and the COATLI optical detection 
(Watson et al. GCN Circ. 22910) 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 (FC)          95          245          147         19.88 +/- 0.34
white              587          607           20         18.11 +/- 0.21
v                  637         1582          117         >18.5
b                  563          756           39         18.34 +/- 0.30
u                  308          557          246         17.90 +/- 0.12
w1                 686         1459           78         18.44 +/- 0.33
m2                 661         1606          117         >18.8
w2                 613         1558          117         >19.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).