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GCN Circular 1491

GRB020813: optical observations; possible host galaxy
2002-08-14T18:19:47Z (22 years ago)
Weidong Li at UC Berkeley KAIT/LOSS <>
W. D. Li, R. Chornock, and A. V. Filippenko (UC Berkeley) report on
behalf of the Lick Observatory and Tenagra Observatory Supernova
Search (LOTOSS; see IAU Circ. 7906):

"We have obtained additional observations of the optical afterglow of GRB020813
with the 0.8-m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory.
We continue to detect the object first reported by Fox et al. (GCN 1470) and
also observed by us (GCN 1473).  An unfiltered observation (600 s) obtained at
14 Aug 04:36 UT shows an extended object at the position of the afterglow.
Another image (600 s unfiltered) obtained at 06:56 UT under better conditions
shows two unresolved objects at that position separated by about 3.7".  We
identify one of these objects with the fading GRB afterglow, and suggest that
the other object is a possible host galaxy (although it could be an unrelated
faint object).  We measured the following unfiltered magnitudes, in addition to
those reported in GCN 1473:

13 Aug 8.3542 UT, mag 18.55 +/- 0.05
14 Aug 4.5972 UT, mag 20.55 +/- 0.25 (host?+GRB)
14 Aug 6.9333 UT, mag 21.08 +/- 0.30 (GRB only) host? = 20.70 +/- 0.25.

We note that the first and third observations imply a power-law decay index
of about -1.44.  This is substantially steeper than the decay rate implied by 
the early observations (GCN 1473, 1474), supporting the hypothesis of Bloom et 
al. (GCN 1476) that the object may have undergone a temporal break."

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