[vsnet-grb-info 19551] GRB 170705A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21294
SUBJECT: GRB 170705A: Swift/UVOT Detection
DATE:    17/07/05 15:08:53 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15 at ucl.ac.uk>

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).
We detect a fading source consistent with the XRT position
(Goad et al., GCN Circ. 21290) and the MASTER (Lipunov et al., GCN Circ. 21291)
and RATIR (Butler et al., GCN Circ. 21293) 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).