GCN Circular 10093
S. B. Cenko (UC Berkeley), M. M. Kasliwal and S. R. Kulkarni (Caltech) report on behalf of a larger collaboration: We have obtained optical spectra of the afterglow of GRB091024 (Marshall et al., GCN 10062) with the Low Resolution Imaging Spectrometer mounted on the 10-m Keck I telescope. Observations began at 11:01 UT on 24 October 2009 (~ 2.1 hours after the burst) and covered the wavelength range from ~ 3500 - 10000 A. In addition to the features identified by Cucchiara, Fox, and Tanvir (CaII H & K, Mg I), we also find strong absorption features we identify as Mg II (2796 / 2803) and Fe II (2344, 2374, 2382, 2586, and 2600) at a common redshift of z = 1.091. The lack of Lyman-alpha absorption places an upper limit of z <~ 1.9 on the redshift of GRB091024.