GCN Circular 7497

S. T. Holland (CRESST/USRA/GSFC) & C. Pagani (PSU) report on behalf of
the Swift/UVOT team:

   The Swift/UVOT observed the field of GRB 080319C starting 210 s
after the BAT trigger (Pagani et al., GCN Circ. 7442
Not found
 
 
).  We detect the
optical afterglow in the v, b, u, and white filters at location of the
KAIT optical afterglow (Li, et al., 2008, GCNC 7441).  The UVOT source
position is

RA(J2000.0) =  17:15:55.49
Dec(J2000.0) = +55:23:30.6

with an estimated uncertainty of +/-0.53 arcsec (radius, 90%
confidence).

   Magnitudes and upper limits are reported below.

Filter    T_start (s) T_stop  Exposure      Mag  Err  Comment
v          334        353       19     18.09 0.30
b          433        443       10     19.02 0.53
u          408        581       39     19.08 0.36
uvw1        383       2410      214    >20.0        3-sigma UL
uvm2        358       2385      175    >19.6        3-sigma UL
uvw2        463       2336      175    >19.9        3-sigma UL
white        227        327       98     18.81 0.08

The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0 .03 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).  The non-detections
in the three ultraviolet filters may indicate that the redshift is
z >~ 3.