GCN Circular 15795

S. R. Oates (UCL-MSSL) and A. Y. Lien (NASA/GSFC/ORAU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140206A
52 s after the BAT trigger (Lien et al., GCN Circ. 15784
Not found
 
 
).
A source consistent with the XRT position (Osborne et al. GCN Circ. 15793
Not found
 
 
)
and the optical positions reported by Oksanen et al. (GCN 15786
Not found
 
 
) and 
Yurkov et al. (GCN 15788
Not found
 
 
) is detected in the initial UVOT exposures. The 
lack of detections in the UV filters suggests a redshift ~2 - 3.

The preliminary UVOT position is:
  RA  (J2000) =  09:41:20.26 = 145.33442 (deg.)
  Dec (J2000) = +66:45:38.6  =  66.76072 (deg.)
with an estimated uncertainty of 0.50 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               52          202          147         15.88 +/- 0.02
v                  596          616           20         15.75 +/- 0.11
b                  522          542           20         16.51 +/- 0.09
u                  264          514          246         16.18 +/- 0.04
w1                 645        17944          963         >20.9
m2               16137        24450         1607         >21.2
w2               21898        22798          886         >21.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).