GCN Circular 21294

S.W.K. Emery (UCL-MSSL) and R. L. C. Starling (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170705A
82 s after the BAT trigger (Starling et al., GCN Circ. 21289
Not found
 
 
).
We detect a fading source consistent with the XRT position
(Goad et al., GCN Circ. 21290
Not found
 
 
) and the MASTER (Lipunov et al., GCN Circ. 21291
Not found
 
 
)
and RATIR (Butler et al., GCN Circ. 21293
Not found
 
 
) detections in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  12:46:48.97 = 191.70404 (deg.)
    Dec (J2000) = +18:18:26.4  =  18.30733 (deg.)
with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence).

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag
white_FC            82          231          147         18.55 +/- 0.06
white              573         1020          186         19.23 +/- 0.11
u                  294          543          246         19.43 +/- 0.19
v                  623         1070           58        >18.3
b                  549          741           39         18.92 +/- 0.26
uvw1               672          692           19        >18.1
uvm2              4617        12950          996        >20.7
uvw2              5644        11420         1137        >21.0

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).