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GCN Circular 13507

GRB 120722A: VLT/X-shooter redshift of the host galaxy
2012-07-23T07:24:14Z (12 years ago)
Valerio D'Elia at ASDC <>
V. D'Elia (ASDC/INAF-OAR), D. Xu (WIS), A. de Ugarte Postigo (IAA-CSIC, DARK), 
D. Malesani (DARK/NBI), , J. P. U. Fynbo (DARK/NBI), P. Goldoni (APC,CEA/Irfu), 
N. R. Tanvir (U. of Leicester) and T. Kruehler (DARK/NBI) 
report on behalf of the GRB/X-shooter collaboration 

We imaged the field of GRB 120722A (Melandri et al., GCN 
13499) with the ESO VLT equipped with the 
X-shooter spectrograph. Observations started on 2012 July 22 at 23:08 UT 
(10 hr after the GRB), for a total exposure time of 80 min in each of 
the UVB, VIS, and NIR arms, covering the wavelength range 3000-25000 AA. 
Within the XRT error circle we noted a SDSS object, which is coincident
with the position of the afterglow reported by Sudilovsky et al. (GCN 13506).
The slit was positioned on this object. The object reported by Sudilovsky et al. (GCN 13506) 
is faintly detected in a combined stack of the ugriz SDSS data, suggesting a significant host contribution. 
The object is also well detected in our R-band acquisition images.

The spectrum is dominated by several nebular emission lines from the candidate host galaxy, 
including [O II], [O III] and Balmer lines (Halpha, Hbeta and Hgamma), 
at a common redshift z = 0.9586. Given the superposition with
the optical afterglow reported by Sudilovsky et al. (GCN 13506), this is likely the
host galaxy of GRB120722A.

We acknowledge excellent support from the ESO staff, in particular Lorenzo Monaco, 
Lorena Faundez and Emanuela Pompei.
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