TITLE: GCN CIRCULAR NUMBER: 6843 SUBJECT: GRB 071003: Keck HIRES spectroscopy DATE: 07/10/03 23:12:24 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley (UCB), J. X. Prochaska (UCSC), J. S. Bloom (UCB), and G. Smith (UCO/Lick) report on behalf of the GRAASP collaboration: We observed GRB 071003 (Schady et al., GCN 6837) with Keck/HIRESr starting at UT 10:24 for one exposure of 1700s. The data were acquired through very high airmass and have a low S/N ratio (~1 per 1.3 km/s pixel at 5000A). We identify no obvious absorption features in either the 2D image nor 1D spectrum. Allowing for the following priors, we place the following upper limits on the GRB redshift: 1. Assuming the GRB host galaxy would emit no flux below the Lyman limit, we infer z_GRB < 3.4 2. Assuming the GRB host galaxy would imprint a damped Lya profile on the spectrum, we infer z_GRB < 2.5 3. Assuming the GRB host galaxy would imprint a strong MgII absorber on the spectrum (EW > 1A), we infer z_GRB < 1. Given these constraints and the U-band detection from Mishra et al. (GCN 6840), it is possible that this GRB is at low redshift. We encourage follow-up observations to search for, or place limits on, a low-redshift host galaxy or associated supernova.