[vsnet-grb-info 2785] GRB 060123: Gemini spectroscopy of the putative
host galaxy
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Tue Jan 31 07:52:07 JST 2006
TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 4622
SUBJECT: GRB 060123: Gemini spectroscopy of the putative host galaxy
DATE: 06/01/30 22:49:55 GMT
FROM: Edo Berger at Carnegie Obs <eberger at ociw.edu>
E. Berger (Carnegie Observatories), P. A. Price (IfA, Hawaii), and D. B.
Fox (Penn State) report on behalf of a larger collaboration:
"We obtained 2x1500 sec spectra of the putative host galaxy located inside
the XRT error circle of GRB 060123 (GCNs 4584,4595,4600) with GMOS on the
Gemini-N 8-m telescope starting on 2006 Jan 30.60 UT. The spectra cover
the range 6400-9100 A and reveal one strong and resolved emission line at
an observed wavelength of 7826.0A, and a possible weaker line at 7590.8A.
The latter line is located on the edge of the atmospheric A-band and and
its reality is therefore questionable. We find three possible
interpretations for the redshift:
[1] The broad line is the (barely resolved) [OII] 3727 doublet at z=1.099.
In this case there is no obvious interpretation for the second line.
[2] The broad line is H-alpha and the weak line line is [OI] 6364 at
z=0.193. In this case we may expect to detect the [NII] and [SII]
doublets, which we do not.
[3] The broad line is [OIII] 5007 and the weak line is H-beta at z=0.562.
In this case we expect to detect [OIII] 4959, which we do not.
Given that the weak line may not be real, and the lack of detection of
various other lines expected in scenarios [2] and [3], we favor the first
interpretation and a redshift z=1.099.
We note that spectra with bluer coverage may be able to confirm or rule
out options [2] and [3] through the detection (or lack thereof) of [OII],
[OIII], and H-beta at their corresponding redshifts."
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