TITLE:   GCN CIRCULAR
NUMBER:  16269
SUBJECT: GRB 140515A: Gemini-N redshift
DATE:    14/05/15 13:55:55 GMT
FROM:    Ryan Chornock at Harvard  <rchornock@cfa.harvard.edu>

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

We observed the field of GRB 140515A (D'Avanzo et al., GCN 16267) using GMOS on 
the Gemini-N 8-m telescope, starting at 10:48 UT on 15 May. A faint source was 
present in the i band acquisition image at a position consistent with the X-ray 
afterglow.  We obtained 2x900s of spectroscopy of this likely afterglow, 
covering the wavelength range 5900-10150 Angstroms at a resolution of R~1200. 
The afterglow has a strong continuum at long wavelengths that sharply drops to 
near zero at wavelengths shortward of lambda~8900 Angs, consistent with the 
onset of Lyman-alpha absorption at z=6.32.  Isolated wavelength intervals of IGM 
transmission exist between 7500 and 8000 Angs (corresponding to z~5.2-5.6 
relative to Ly-alpha).  Further analysis is ongoing.

We acknowledge excellent support from Gemini observer Lucas Fuhrman.