GCN Circular 8450

S. T. Holland (CRESST/USRA/GSFC) & T. Sakamoto (NASA/UMBC) report on
behalf of the Swift/UVOT team:

        The Swift/UVOT observed the field of GRB 081029 starting 2708 s
after the BAT trigger (Sakamoto et al., 2008, GCNC 8435).  The late
start to the follow-up observations is due to an Earth limb constraint
at the time of the BAT trigger.  We detect the optical afterglow
(Rykoff et al., GCNC 8436) in the v, b, and white filters.  This is
consistent with a redshift of z = 3.8479 (D'Elia, et al., 2008, GCNC
8438).  The refined UVOT source position is

   RA (J2000.0) =  23:07:05.35 = 346.77229 (deg)
  Dec (J2000.0) = -68:09:19.8  = -68.15549 (deg)

with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence,
statistical + systematic).

      Magnitudes and 3-sigma upper limits are reported below.  TSTART
and TSTOP are the start and stop times of the exposure, in seconds
since the BAT trigger.  Exposure is the total exposure time, in
seconds, during that interval.

Filter   TSTART    TSTOP   Exposure       Mag  Err  Comments
     v      2687     2887        197     19.02 0.20
            8557     8757        197     18.66 0.21
     b      3072     3272        197    >20.5        3-sigma upper limit
            4507     4707        197     20.05 0.20
     u      2867   21,932       1601    >21.9        3-sigma upper limit
   uvw1     4097   21,019       1968    >21.8        3-sigma upper limit
   uvm2     3892   16,685       1590    >21.7        3-sigma upper limit
   uvw2     3482   15,250       1279    >21.7        3-sigma upper limit
  white     2708     7856        147     20.50 0.30
            4712     4912        197     19.41 0.10

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 photometric
system described in Poole et al. (2008, MNRAS, 383,627).  The
power-law decay index in the v band between 8557 and 15,864 s is
consistent with no decay.