TITLE:   GCN CIRCULAR
NUMBER:  14744
SUBJECT: GRB 130603B: Short GRB afterglow spectrum from GTC
DATE:    13/06/04 00:38:17 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

C. C. Thöne (IAA-CSIC), A. de Ugarte Postigo (IAA-CSIC/DARK), J. Gorosabel (IAA-CSIC/UPV-EUH), N. Tanvir (U. Leicester), and J. P. U. Fynbo (DARK/NBI) report:

We obtained spectroscopy of the afterglow (GCN 14742, Levan et al, GCN 14743, de Ugarte Postigo et al.) of the short GRB 130603B (GCN 14735, Melandri et al.) with OSIRIS/GTC starting at 23:05 UT. Three spectra of 900s were obtained with grism R1000B. The afterglow lies on top of an SDSS galaxy as noted in Levan et al.

The spectrum shows a strong trace of the afterglow with absorption lines of the Ca II doublet as well as MgII and MgI. Superimposed are emission lines from the host galaxy of [OII], [OIII], Hbeta and Hgamma extended in the spatial direction. Absorption and emission lines lie at a common redshift of z=0.356. We therefore determine this to be the redshift of the short GRB and its host galaxy. 

We acknowledge the excellent support by the GTC staff, in particular Rene Rutten and David Garcia.