TITLE:   GCN CIRCULAR
NUMBER:  15307
SUBJECT: GRB131004A: Magellan Redshift
DATE:    13/10/05 00:56:31 GMT
FROM:    Ryan Chornock at Harvard  <rchornock@cfa.harvard.edu>

R. Chornock, R. Lunnan, and E. Berger (Harvard) report:

We observed the optical afterglow (Xu et al., GCN 15304; Malesani et al., GCN 
15305; Kopac et al., GCN 15306) of the possible short GRB 131004A (Hagen et al., 
GCN 15303) using LDSS-3 on the 6.5-m Magellan Clay Telescope.  A sequence of 
3x1200s spectroscopic exposures of the afterglow began at 23:44 on 4 October UT. 
  A preliminary reduction reveals a flat continuum with superposed weak emission 
lines from [O II], H-beta, and [O III] at a common redshift of 0.717.  Possible 
weak features consistent with Ca II H+K absorption at this same redshift are 
also present.