GCN Circular 7941

P. Ward (MSSL-UCL) and H. Ziaeepour (UCL-MSSL) report on behalf of the 
Swift/UVOT team:

The Swift Ultra-Violet/Optical Telescope (UVOT) started observing
GRB 080703 (Rykoff et al. GCN 7935
Not found
 
 
, Ziaeepour et. al, GCN 7936
Not found
 
 
) ~100 
seconds after the trigger.

A quickly fading candidate afterglow is found in the UVOT White and V 
filters. The preliminary Swift/UVOT position of the optical afterglow 
candidate is:

  RA(J2000)  = 06:47:12.639 = 101.8027
  DEC(J2000) = -63:13:08.96 = -63.2192

with a 1-sigma error radius of about 0.5 arcsec.
The following table gives the measured magnitudes:

Filter T_start T_stop Exp     Mag

White  101    200    99.8     17.40 +/- 0.03
White  857    956    99.8     20.27 +/- 0.35
White  5905   6102   196.6    21.29 +/- 0.49
White  5905   19222  869.5  > 21.77 (1.9-sigma)
V      207    606    399.8    18.02 +/- 0.10
V      963    1362   399.8    19.06 +/- 0.27
V      6315   6512   196.6  > 19.65 (0.2-sigma)
V      6315   12021  1081.7 > 20.83 (0.9-sigma)
B      687    1788   78.9   > 19.48 (1.8-sigma)
B      663    1764   99.0   > 19.33 (1.5-sigma)
UVW1   638    1885   99.9   > 19.55 (0.1-sigma)
UVM2   613    1878   118.7  > 19.67 (1.7-sigma)
UVW2   718    1829   79.1   > 19.55 (0.9-sigma)


The values quoted above are in the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627). No correction has been
made for the expected extinction corresponding to E(B-V) of
0.071 mag in the direction of the burst (Schlegel et al. 1998).