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
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.