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GCN Circular 12777

GRB 111229A: Gemini-South Redshift
2011-12-30T02:32:04Z (12 years ago)
Antonino Cucchiara at LBNL <>
A. Cucchiara (UCSC/UCO Lick), A. J.  Levan (U. Warwick), 
and N. Tanvir (U. Leicester) report:

On December 30.05 UT (157 minutes after the BAT trigger) 
we observed the field of GRB 111229A (Lien et al., GCN 12774) 
using GMOS-South on the Gemini-South 8-m telescope.  

An optical afterglow is detected at a position reported by
Nicuesa Guelbenzu et al. (GCN 12775).
Subsequent spectroscopic observation of the optical afterglow of 
GRB 111229A  (range 5900-10080 Angstroms) reveals several absorption 
features, including FeII2586,2600, MnII2606, MgII2796,2803 
and MgII2853 at a common redshift of 1.3805.

We therefore suggest this to be the redshift of GRB 111229A.

We thank the Gemini staff for performing this observation, 
in particular Pascale Hibon.
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