GCN Circular 3808
GRB 050813: Gemini Spectra Revisited R. J. Foley, J. S. Bloom (University of California, Berkeley), and H.-W. Chen (MIT) report: "We have performed an independent reduction and analysis of the spectra of galaxies B and C in the XRT error circle of GRB 050813 (GCN 3788), and a as yet unnamed galaxy to the north-east (referred to as X below) obtained on Aug 14.35 UT with GMOS on Gemini-North under program GN-2005B-Q-6 and originally reported in GCN 3801 by Berger. Inspection of the spectrum of galaxy X shows it to be at redshift z = 0.722 (consistent with the redshift listed in GCN 3801 for galaxies B and C) with obvious Ca H&K and G-band absorption but no signs of H gamma or H beta absorption. Inspection of the spectrum of galaxy B shows it to be at redshift z = 0.718 with obvious Ca H&K absorption, but again, no signs of H gamma or H beta absorption. Inspection of the spectrum of galaxy C shows it to not definitively be at z = 0.722. Although there are broad dips in the spectrum which may correspond to Ca H&K at z = 0.722, there are other features which conflict with this conclusion. There are narrow emission lines at 7353 and 7519 A observed (which would be 4270 and 4367 A at z = 0.722). The Ca H&K lines of galaxy X have a velocity width of 591 +/- 97 km/s. The presence of G-band absorption and a lack of emission lines points towards an old stellar population. The Ca H&K lines of galaxy B have a width of 340 +/- 93 km/s. There is also a strong (EW_observed = -6.0 A) unidentified absorption line at 7402 A. If we place this line at the redshift of the galaxy, we notice that this could be Ti I 4305. There is an offset of 116 km/s between the line and the fiducial redshift if this is the correct identification. Another possibility is this line is due to Mg II 4481 at z = 0.65." This message may be cited.