TITLE:   GCN CIRCULAR
NUMBER:  16125
SUBJECT: GRB 140419A: Gemini-N redshift
DATE:    14/04/19 13:21:37 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick),
A. Cucchiarra (ORAU/GSFC), D. Perley (Caltech), S. B. Cenko (GSFC) 
D. Coulson, L. Fuhrman report:

We observed the afterglow of GRB 140419A (Marshall et al. GCN 16118;
Zheng et al. GCN 16119; Guver et al. GCN 16120; Butler et al. GCN 16121)
with the GMOS-N spectrograph on Gemini-N.  Observations began
at 06:24 UT, approximately 2.3 hr post burst, and two different
settings covered a total wavelength range from about 4400AA to 10100AA.

The spectra reveal several strong absorption lines and in particular
there is a marked break at about 6027 AA which we identify as
Ly-a at a redshift z=3.956.  Blueward is a clear Ly-a forest.
At the same redshift we see strong lines of CIV (1548/1551) and
SiIV (1394/1403), and weaker lines of NV (1239/1243), CII (1335),
SiII (1527), AlII (1671).  We therefore infer z=3.956 as the redshift of 
the burst.

We note that there also appears to be an intervening system at z=2.686.

[GCN OPS NOTE(19apr14): Per author's request, DC and LF were added
to the author list.]