[vsnet-grb-info 14231] GRB 131128A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15545
SUBJECT: GRB 131128A: Swift/UVOT Detection
DATE:    13/11/29 11:54:03 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

S. R. Oates (UCL-MSSL) and E. Sonbas (NASA/GSFC/Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 131128A
91 s after the BAT trigger (Sonbas et al., GCN Circ. 15533).
A source consistent with the optical position (Xu et al., GCN Circ. 15535) 
and the enhanced Swift-XRT position (Goad et al., GCN Circ 15538) is 
detected in the first UVOT white exposure only. A USNO-B1 catalogued star 
heavily contaminates the position of the optical candidate afterglow 
making the measurement very complicated.

Preliminary detection 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)          91          241           147        19.11 +/- 0.11
white		    583         1181          206    	 >21.44
u (FC)              303         552           245        >20.2
u                   303	        1130          285    	 >20.3
v                   632	        1231          78         >19.0
b                   558         1155          58         >19.8
w1                  683	        1275          53         >18.9
m2                  657         1255          78         >19.0
w2                  608	        1206          78         >19.4

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