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GCN Circular 9557

GRB 090621B: P60 Observations
2009-06-22T17:40:24Z (15 years ago)
S. Bradley Cenko at Caltech <>
S. B. Cenko (UC Berkeley), A. J. Levan (U. Warwick), M. M. Kasliwal, S. R.
Kulkarni (Caltech) report on behalf of a larger collaboration:

We have imaged the field of the short GRB090621B (Curran et al., GCN 9545)
with the automated Palomar 60-inch telescope.  Observations consisted of
20 x 180 s images in the i' filter at a mean epoch of 5:37 UT on 22 June
2009 (~ 7.5 hours after the burst).

We detect the candidate afterglow reported by Levan et al. (GCN 9547) and
Galeev et al. (GCN 9549) at low significance.  Using several USNO-B
sources in the field for reference, we measure a magnitude of I ~ 22.9.
No other sources are detected inside the revised XRT error circle
(Beardmore et al., GCN 9550).

Directly comparing our P60 image with the WHT image from ~ 2 hours after
the burst (GCN 9547), we find the candidate has faded marginally by 0.5 +-
0.3 mag.  Further late-time observations will be needed to confirm if this
is the optical afterglow of GRB090621B.
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