TITLE:   GCN CIRCULAR
NUMBER:  8747
SUBJECT: GRB 081228: Swift/UVOT  Upper Limits
DATE:    08/12/28 16:00:24 GMT
FROM:    Wayne Landsman at GSFC/SSAI  <wayne.b.landsman@nasa.gov>

W. Landsman (GSFC) and K. L. Page (U. Leicester) report on behalf of the 
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 081228 82s 
after the BAT trigger (Page et al., GCN 8742).
The exposure time was limited by observing constraints until about 1 
hour after the trigger.   We do not detect any source at the refined 
Swift XRT position (Page & Evans GCN 8746).   UVOT magnitude 3-sigma 
upper limits in a 5" aperture are reported in the following table:

Filter   T_start     Exp(s)  Mag (3-sigma upper limit)
------------------------------------------------------
white       82         37      > 20.0
white     4679        137      > 20.7
v         3653        197      > 19.3
b         4473        197      > 20.3
u         4268        197      > 20.0
uvw1      4063        197      > 20.0
uvm2      3858        197      > 20.0
uvw2      9102        886      > 20.9

The quoted upper limits have not been corrected for the expected 
Galactic extinction along the line of sight of E_(B-V) = 0.16 mag.   All 
photometry is on the UVOT photometric system described in Poole et al. 
(2008, MNRAS, 383, 627).