GCN Circular 7131

P. J. Brown, M. M. Chester (PSU), R. L. C. Starling
(U. Leicester), and M. Stamatikos (NASA/ORAU)
report on behalf of the Swift/UVOT team:

Swift/UVOT observed the field of GRB 071122 (trigger
#297114) starting 145 s after the BAT trigger
(Stamatikos et al., GCN Circ. 7121
Not found
 
 
).  A faint source
is detected in the first white exposure at a position
of 18h 26m 25.38s, Dec = +47d 4m 30.8s, consistent
with the optical afterglow found by Cenko (GCN Circ.
7125
Not found
 
 
) and the revised XRT position (Evans et al.,
GCN Circ. 7126
Not found
 
 
).  The afterglow is detected at a
level of 4 sigma and has a magnitude of
white=20.8 +- 0.3 (one sigma error), with an exposure
midpoint time of 196 s after the trigger.  It is
not detected in subsequent exposures in white
or the other 6 filters.  The detection and 3-sigma
upper limits in the coadded frames are summarized
in the following table:

Filter       T_start(s)   T_stop(s)     Exp(s)    Mag/3-sigma UL

white        145          245           100       20.8 +- 0.3
white        748          1483          119       >21.3
v            252          1517          823       >21.2
b            733          1469          30        >19.6
u            708          1444          40        >19.4
uvw1         684          703           20        >19.2
uvm2         658          1395          59        >18.7
uvw2         763          1508          40        >18.8

The values quoted above are not corrected for the
expected Galactic extinction corresponding to a
reddening of E(B-V) = 0.048 mag towards the direction
of the burst (Schlegel et al. 1998).