GCN Circular 3716
M. Holman (CfA), P. Garnavich (Notre Dame), K.Z. Stanek (Ohio State) Spectra of the afterglow of GRB 050730 (Holland et al. GCN 3704) were obtained with the Magellan Observatory Baade Telescope and IMACS imaging spectrograph beginning 2005 July 30 23:57 (UT). The spectra cover 360 to 950 nm with a dispersion of 0.74 A/pix. We find a clear Ly-alpha absorption system with the GRB flux reaching zero between 598 nm and 609 nm. This confirms the redshift of 3.97 found for the burst by Chen et al. (GCN 3709) and Rol et al. (GCN 3710). An image of the GRB field was obtained July 30 23:10 (UT) with IMACS and the afterglow flux calibrated with Landolt standard SA110-360. We estimate the afterglow brightness at R=17.50+/-0.05 mag. A star to the west of the afterglow at 14:08:14.62 -03:46:29 (2000) has a brightness of R=17.18+/-0.05 mag. A plot of the spectrum and the image of the afterglow obtained with IMACS are available at http://www.nd.edu/~pgarnavi/grb050730 .