TITLE: GCN CIRCULAR NUMBER: 9028 SUBJECT: GRB 090323 Gemini-South Redshift DATE: 09/03/24 07:18:48 GMT FROM: Ryan Chornock at UC Berkeley R. Chornock, D. A. Perley, S. B. Cenko, and J. S. Bloom (UC Berkeley) report on behalf of a larger collaboration: We performed spectroscopy on the afterglow of GRB 090323 (Ohno et al., GCN 9021; Updike et al., GCN 9026; Cenko and Perley, GCN 9027) using Gemini-South (GMOS) starting at 05:58 UT on 2009-03-24, approximately 30 hours after the trigger. We conducted a series of four exposures of 600 seconds, two using the B600 grating centered at 6000 Angstroms and two with the R400 grating centered at 8000 Angstroms. The first spectrum shows strong absorption blueward of 5580 Angs, which we identify as the onset of the Lyman-alpha forest at z=3.6. There are also narrow absorptions with multiple components from C IV, O I, C II, and Si IV at a consistent redshift of z=3.57. Further analysis is ongoing. We would like to thank the Gemini-S staff, in particular Etienne Artigau, Lucas Fuhrman, and Benoit Neichel, for their support with these observations.