TITLE:   GCN CIRCULAR
NUMBER:  15966
SUBJECT: GRB 140311A: Gemini-North redshift
DATE:    14/03/12 16:33:51 GMT
FROM:    Ryan Chornock at Harvard  <rchornock@cfa.harvard.edu>

R. Chornock (Harvard), D. B. Fox (Penn State), N. R. Tanvir (U. Leicester), and 
E. Berger (Harvard) report:

We obtained 2x900s of spectroscopy of the optical afterglow (Xu et al., GCN 
15947) of GRB 140311A (Racusin et al., GCN 15944) using GMOS on the 8-m Gemini-N 
telescope beginning at 12:56 UT on March 12. We used the R831 grating to cover 
the wavelength range of 6950-9075 Angs at a resolution of approximately 2.8 
Angs. Our data exhibit a broad damped Lyman-alpha feature centered near 7250 
Angs (redshift~4.95), in agreement with previous reports from Gemini-South 
(Tanvir et al., GCN 15961) and NOT (D'Avanzo et al., GCN 15964).  In addition, 
we detect many metal lines, including C II, C II*, O I, O I*, Si II, Si II*, and 
Si IV at a common redshift of 4.954, which we adopt as the redshift of the GRB.

We thank the Gemini staff, particularly Jesse Ball, for their excellent 
assistance in obtaining these data.