GCN Circular 5051

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
Not found
 
 
) and confirmed by Cenko et al. (GCN5048
Not found
 
 
), 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."