GCN Circular 5607
Subject
GRB 060923C: Gemini Observations and Afterglow Candidate
Event
Date
2006-09-25T03:32:08Z (20 years ago)
From
Derek Fox at PSU <dfox@astro.psu.edu>
D.B. Fox (Penn State) reports on behalf of a larger collaboration:
"We have imaged the XRT position of GRB060923C (Stamtikos et al., GCN
5591) in the K-band with Gemini-North + NIRI on two occasions with
mean epochs of 05:39 UT and 08:34 UT, respectively, on 24 Sep 2006.
We detect the (I-band) source of Rau et al. (GCN 5598; hereafter
source "A") as well the additional (J-band) sources "B" and "C" of
Covino et al. (GCN 5604). At both epochs, these are the only sources
consistent with the XRT localization.
Although we lack an absolute photometric calibration at this time, we
observe a relative decline of Source B by ~0.4 mag in K-band between
these two epochs. The magnitudes of Sources A and C are not observed
to vary, being consistent across our two epochs to within 0.1 mag.
Noting as well the indication for Source A in the DSS (GCN 5598), and
that Source C is clearly extended in our images, we suggest that
Source B is the afterglow of GRB060923C. In this case, the absence
of detectable afterglow light in the early Keck+LRIS I-band images may
indicate a high-redshift origin or high line-of-sight extinction for
this burst."