[vsnet-grb-info 12566] GRB 121027A: X-shooter redshift confirmation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13930
SUBJECT: GRB 121027A: X-shooter redshift confirmation
DATE:    12/10/30 09:05:32 GMT
FROM:    Thomas Kruehler at Dark Cosmology Center  <tom at dark-cosmology.dk>

T. Kruehler (DARK), N. R. Tanvir (U. Leicester), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI),
D. Malesani (DARK), J. Fynbo (DARK), A. Melandri (INAF-OAB), A. J. Levan (U. Warwick), 
K. Wiersema (U. Leicester), S. Schulze (PUC and MCSS), P. Goldoni (APC,CEA/Irfu), 
H. Flores (Obs. Paris) and L. Kaper (U. Amsterdam) report on behalf of a larger collaboration:

We observed the optical/NIR counterpart  (Starling et al. GCN 13911, 
Levan et al. GCN 13920, Sudilovsky et al. GCN 13926) of GRB 121027A 
(Evans et al. GCN 13906) with the VLT/X-shooter spectrograph, 
beginning at Oct 30 2012 04:52 UT, which is 2.89 days after the GRB.

We identify emission lines of [OIII]4959 and [OIII]5007, and several absorption
lines of CIV, AlII, AlIII, MgI, MgII and FeII at a common redshift of z=1.773.  This 
confirms the provisional redshift given in Tanvir et al. (GCN 13929) for this GRB.

We note that the afterglow remains remarkably bright at 2.9 days post burst.