GCN Circular 16932

N.P. M. Kuin (UCL-MSSL) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 141020A
92 s after the BAT trigger (Cenko et al., GCN Circ. 16928
Not found
 
 
). A source
consistent with the XRT position  (Osborne et al. GCN Circ. 16931
Not found
 
 
)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  14:59:59.15 = 224.99646 (deg.)
    Dec (J2000) = +55:18:46.7  =  55.31297 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).

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               92          241          147         18.02 +/- 0.04
v                  634         1409           58         18.40 +/- 0.23
b                  559          753           39         18.66 +/- 0.18
u                  304          554          246         18.48 +/- 0.09
w1                 683         6660          471        >20.9
m2                1238         6455          413        >21.1
w2                 784        11546         1196        >21.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).