GCN Circular 7298
Subject
GRB 080210: Keck photometry
Event
Date
2008-02-13T00:12:19Z (18 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, M. Modjaz, J. S. Bloom, D. Poznanski, A. Miller, and D.
Kocevski (UC Berkeley) report:
On the night of 2008-02-12 (UT), we observed the field of GRB080210
(Grupe et al., GCN 7281) using Keck I (+LRIS) for 600s (R) and 900s (g).
We detect the GRB afterglow at the position noted by Klotz et al. (GCN
7280) and Grupe et al.
Calibrating relative to seven stars from the SDSS calibration table
given in GCN 7282 (Cool et al.), we measure the following magnitudes (at
UT = 15:32, 55.7 hours after the BAT trigger):
R = 24.03 +/- 0.06
g = 25.20 +/- 0.07
The quoted uncertainty is photometric only and does not include scatter
in the field calibration relative to SDSS (which is significant.)
Compared to the photometry given by Updike et al. (GCN 7288) this
suggests an unusually slow decay rate of alpha~0.85. This may suggest
the presence of an underlying host galaxy, but the source appears
pointlike in our images and the redshift of z=2.1 (Jakobbson et al., GCN
7286) would argue against a large host galaxy contribution. The X-ray
afterglow* also appears to be decaying slowly.
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* http://astro.berkeley.edu/~nat/swift/00302888/bat_xrt.jpg.