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GCN Circular 12759

GRB 111228A: MMT Redshift
2011-12-29T08:16:27Z (13 years ago)
Edo Berger at Harvard <>
J. Dittman, T. Laskar, and E. Berger (Harvard) report:

"Starting on 2011 December 29.312 UT (15.7 hours after the burst) we
used the Blue Channel spectrograph mounted on the MMT 6.5-m telescope
to observe GRB111228A (GCN #12737).  Our spectra cover the range
3400-8500A and reveal absorption lines of MgII and FeII at a common
redshift of z=0.714, which we consider to be the redshift of
GRB111228A.  Additional observations are in progress."
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