GCN Circular 3949
Subject
Gemini Spectroscopy of GRB 050908
Event
Date
2005-09-08T14:31:28Z (20 years ago)
From
Ryan Foley at UC Berkeley <rfoley@astro.berkeley.edu>
R. J. Foley (UCB), H.-W. Chen (UChicago), J. S. Bloom (UCB), and Jason X.
Prochaska (UCO/Lick Observatory) report:
"We obtained 2x1200 sec dithered exposures of the optical candidate (GCN
3943) of GRB 050908 using GMOS on the Gemini-North telescope with the B600
grating. The observations started at 20050908.39 UT (~ 4 hrs after the
initial Swift trigger). We measure a redshift of z = 3.3437 +/- 0.0002
based on a series of absorption features due to HI 1215, SiIII 1206, SiII
1260, SiIV 1393, 1402, and CIV 1548, 1550. We also observe a flux
discontinuity at 5285.9 Ang at the onset of the Lya forest absorption from
the intergalactic medium. Our redshift measurement is somewhat lower than
but still consistent with the redshift of 3.350 +/- 0.005 reported by
Fugazza et al. (GCN 3948). Using the HI 1215 absorption line, we estimate
a neutral hydrogen column density of log N(HI) ~ 19.2.
In addition to this system, which we contend is the redshift of the host
galaxy, we see several other, intervening systems at z = 2.81 and 3.039.
The system at z = 2.81 is particularly interesting. It shows CIII 1909 and
CIV 1549 emission."