GCN Circular 7437
R. J. Foley, D. Perley, and J. S. Bloom (UCB) on behalf of the GRAASP collaboration report: We obtained 2x1800 sec exposures of the optical afterglow (GCN 7428, 7430) of GRB 080319B (GCN 7427) using GMOS on the Gemini-South telescope with the R831 grating. The observations started at 20080319.35 (~2 hours after the initial Swift trigger). Initial reductions show a featureless continuum with no strong absorption systems, emission lines, or breaks. Given our wavelength range of 595 - 815 nm, we can place the following constraints on the redshift (in order of descending confidence): (1) The lack of a Lyman limit implies z < 5.5. (2) The lack of damped Lya or obvious Lya forest implies z < 3.9. (3) The lack of obvious Mg II absorption implies z < 1.1. Further analysis is in progress.