TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4729 SUBJECT: GRB060210: Gemini absorption spectroscopy DATE: 06/02/10 09:12:53 GMT FROM: Antonino Cucchiara at PSU A. Cucchiara (Penn State), D. B. Fox (Penn State), and E. Berger (Carnegie Observatories) report on behalf of a larger collaboration: "We have observed the optical afterglow (Fox & Cenko, GCN 4723) of GRB 060210 (Beardmore et al., GCN 4724) with the GMOS instrument on Gemini-North. Examination of a reduced 1500-s spectrum of the afterglow reveals a strong continuum break at roughly 6000 Angstroms, with only intermittent transmission blueward of this wavelength and multiple strong absorption features to the red, including the NV 1239,1243 doublet, the CIV 1548,1550 doublet, and an array of Si transitions, at the common redshift of z=3.91. We propose this as the redshift of GRB 060210." We acknowledge the rapid response effort of Gemini personnel that yielded these data, and in particular observer I. Song.