GCN Circular 8431
Subject
GRB081028: UVOT detection of a brightening afterglow
Event
Date
2008-10-28T15:40:08Z (17 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P. Schady (MSSL-UCL) and C. Guidorzi (INAF-OAB) report on behalf of
the Swift/UVOT team:
Further to the UVOT observations of GRB 081028 reported in GCN Circ.
8430 (Schady et al.), we report an afterglow detection at the position
of the optical counterpart (GCN Circ. 8424, GCN Circ. 8425) in later
UVOT observations, from 10,000s after the BAT trigger. This is
suggestive of a re-brightening of the afterglow consistent with the
time of the brightening observed in the XRT light curve (Guidorzi et
al., GCN Circ. 8429). The afterglow is detected in the v, b and u-band
filters. The detection of the afterglow in the u-filter suggests a
photometric upper limit on the redshift of z < ~2.3.
The magnitudes of the afterglow and 3-sigma upper limits are reported
below:
Filter Tstart(s) Tstop(s) Exp(s) Magnitude/3-sig UL
v 4050 5684 393.2 > 20.13
v 10740 28995 1770.3 20.23 +/- 0.19
b 4870 6504 393.3 > 20.79
b 17436 35567 1433.5 20.19 +/- 0.14
u 4665 6299 393.2 > 20.53
u 16524 34778 2539.8 21.21+/- 0.26
uvw1 4460 6094 393.2 > 20.61
uvw1 15618 33865 2656.7 > 21.89
uvm2 4255 5889 393.2 > 20.51
uvm2 21399 29784 2428.5 > 21.66
uvw2 5281 5480 196.6 > 20.23
uvw2 29001 28082 1771.2 > 20.61
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).