TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3088 SUBJECT: GRB 050126: Redshift determination DATE: 05/03/12 02:37:37 GMT FROM: Edo Berger at Carnegie Obs E. Berger (Carnegie Observatories), S.B. Cenko and S.R. Kulkarni (Caltech) report on behalf of a larger collaboration: "We obtained spectra of the host galaxy of GRB 050126 with the Echelle Spectrograph and Imager (ESI) mounted on the Keck II telescope. Inspection of the 2-d and extracted spectra reveals a single emission line at an observed wavelength of 8536.5 angstrom with continuum emission both redward and blueward of the line. Interpreted as [OII]3727 this indicates a redshift of z=1.29, the first for any Swift GRB. At this redshift, given a fluence of 2e-6 erg/cm^2 (Berger et al. astro-ph/0502468), the isotropic-equivalent gamma-ray energy is 8.7e51 erg."