GCN Circular 7577

P. Schady (MSSL-UCL) reports on behalf of the Swift-UVOT team:

The Swift/UVOT performed a Target of Opportunity observation on the SuperAGILE 
GRB 080408 (Soffitta et al., GNCN Circ. 7571), starting ~7hrs after the 
trigger. Observations were made in the b, u and uvw1 filters. The optical 
afterglow is not detected in any of these filters at the XRT position (Page et 
al., GCN Circ 7576) down to the following 3 sigma upper limits:

Filter  Tstart  Exp   Mag UL (3sig)
         (hrs)   (s)
b       7.12    185   > 19.96
u       7.06    200   > 19.63
uvw1    6.95    399   > 19.97

The above magnitudes are not corrected for the Galactic extinction 
corresponding to a reddening of E(B-V)=0.04 mag (Schlegel et al., 1998, ApJS, 
500, 525). The photometry is on the UVOT flight system described in Poole et 
al. (2008, MNRAS, 383, 627).