TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5051 SUBJECT: GRB 060502: APO Spectroscopic Observations DATE: 06/05/02 10:12:43 GMT FROM: Hsiao-Wen Chen at U Chicago H.-W. Chen (U Chicago), R. McMillan (APO), A. Bender (U Colorado), D. York, and D. Lamb (U Chicago) report on behalf of a larger collaboration: "We observed the afterglow of GRB060502A reported by La Parola et al. (GCN 5047) and confirmed by Cenko et al. (GCN5048), using the Dual Imaging Spectrograph (DIS) with a 1.5-arcsec slit on the 3.5 m telescope at the Apache Point Observatory. The observations started at UT 05:52:33 on May 2, 2006, ~ 2.8 hours after the inital Swift/BAT trigger, and were carried out under a mean seeing condition of 1.3 arcsec in a sequence of two 1800-sec exposures. The final stacked spectrum covers the spectral range from 3800 Ang to 8500 Ang with a spectral resolution of 2.4 Ang per pixel, and appears to be featureless. The abundant fluxes observed below 4000 Ang and the lack of spectral discontinuity below 4500 Ang indicate that the GRB originated at redshift z < 2.2. We determine a tentative redshift for the GRB afterglow at z=0.099 +/0.001 based on the tentative identifications of CaII H&K absorption features at around 4322 and 4361 Ang. Further analysis is underway. This message may be cited."