GCN Circular 8654

S. Immler (CRESST/UMD/GSFC), S. T. Holland (CRESST/USRA/GSFC), and H. A. 
Krimm (CRESST/GSFC/USRA) report on behalf of the Swift UVOT team:

Further analysis of Swift Ultraviolet/Optical Telescope (UVOT) data of 
GRB 081210 (Krimm et al., GCN Circ. 8648
Not found
 
 
), starting 80 sec after the BAT 
trigger, gives a detection of an optical source consistent with the 
enhanced XRT position (Osborne et al., GCN Circ 8650) in the white and u 
filters at 12.6-sigma and 3.8-sigma levels of confidence, respectively. 
The source is not detected in any of the other UVOT filters at the 
limiting magnitudes reported below.

Filter Tstart(s) Tstop(s)  Exp(s)  Magnitude

wh      80       1009     318      19.91+/-0.08
u      292        716     265      20.15+/-0.29
b      548        741      39      >19.78  (3-sigma UL)
uvw2   598       5251     235      >20.47  (3-sigma UL)
v      622        816     244      >19.99  (3-sigma UL)
uvm2   647        840     136      >19.55  (3-sigma UL)
uvw1   672        866      39      >18.74  (3-sigma UL)

The values quoted above are in the UVOT photometric system (Poole et al. 
2008, MNRAS, 383, 627) and are not corrected for the expected Galactic 
extinction along the line of sight which corresponds to a reddening of 
E(B-V) = 0.077 mag (Schlegel et al. 1998).

The event data in the white filter shows a flare peaking at 
approximately 130 s after the BAT trigger, which approximately coincides 
with the flare seen in the X-ray light curve (Evans et al., GCN Circ 8652).