GCN Circular 13133
D. A. Perley (Caltech) and N. R. Tanvir (U. Leicester) report on behalf of a larger collaboration: On March 27 starting at 06:01 UT (186 minutes after the BAT trigger) we began spectroscopic observations of the optical afterglow of GRB 120327A (Sbarufatti et al., GCN 13123) using GMOS-South on the Gemini-South 8-m telescope. We acquired four exposures of 800s each using the B600 grating, with wavelength coverage between 3865-6680 Angstroms. In the reduced spectrum we identify a strong damped Lyman-alpha system at z=2.81 as well as numerous narrow absorption lines corresponding to (among others) CIV, CII, OI, SiII at the same redshift, as well as possible Lyman-beta. We therefore identify this as the redshift of the GRB. We thank German Gimeno and the Gemini staff for prompt execution of the observations.