TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3542 SUBJECT: GRB 050416(a): Host Galaxy Redshift Determination DATE: 05/06/10 00:45:36 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko, S. R. Kulkarni, A. Gal-Yam (Caltech) and E. Berger (Carnegie Observatories) report on behalf of the Caltech-NRAO-Carnegie Collaboration: We have obtained 2 x 30 minute spectra of the host galaxy of GRB 050416 (a) with the Low Resolution Imaging Spectrometer mounted on the 10-m Keck I Telescope. Observations were taken on 6 June, 2005 UT. We identify several emission lines including [OII], H-beta, H-gamma, and H- delta at a redshift of z = 0.6535 +/- 0.0002. The spectrum indicates the host galaxy is faint and blue with large amounts of ongoing star formation. We note the redshift is consistent with the prediction of Fox (3408) based on the afterglow detection in the Swift UVOT UVW2 filter. Using a fluence of 3.8e-7 erg/cm^2 (10 - 350 keV, GCN 3273), we find an isotropic gamma-ray energy release of 7.0e50 ergs.