TITLE:   GCN CIRCULAR
NUMBER:  18984
SUBJECT: GRB 160203A: Swift/UVOT Detection
DATE:    16/02/03 12:50:43 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and P. D'Avanzo (INAF-OAB) report on behalf of 
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160203A 
151 s after the BAT trigger (D'Avanzo et al., GCN Circ. 18979).
A fading source consistent with the optical position (Kruehler et al. 
GCN Circ. 18980) is detected in the initial UVOT exposures in the white 
filter.

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           151          301          147         20.56 ± 0.3
white            10022        10928          885         21.9 ± 0.3
b                 4946         5146          197        >20.7
u                  309          472          160        >19.5
v                 5562         5762          197        >19.7
uvw1              5972         6171          197        >19.7
uvm2              5766         5966          197        >19.6
uvw2              5357         5557          197        >19.9

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.07 in the direction of the 
burst (Schlegel et al. 1998).