TITLE: GCN CIRCULAR NUMBER: 19350 SUBJECT: GRB 160425A VLT/X-shooter redshift DATE: 16/04/26 09:28:42 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir (U. Leicester), D. Xu (NAO/CAS), T. Kruehler (MPE), D. Malesani, J. P. U. Fynbo (DARK/NBI), G. Pugliese (U. Amsterdam), A. J. Levan (U. Warwick), Z. Cano (U. Iceland) report on behalf of a larger collaboration: We observed the optical counterpart of the unusual GRB 160425A (Krimm et al., GCN 19343) with the ESO Very Large Telescope UT 2 (Kueyen) equipped with the X-shooter spectrograph, covering the wavelength range 3500-20000 AA. Observations started on April 26.26 UT (approx 6.9 hr after the GRB) and consisted of 4 exposures of 1200 s each. In our acquisition images, we detect an extended object consistent with the position of the UVOT counterpart, whose morphology exhibits two knots separated by ~1.2". That object is faintly visible in the digitized sky survey, and is likely the host galaxy of GRB 160425A. The spectrum reveals two distinct systems at z=0.555, based on emission lines of Halpha, Hbeta, [O III], [O II] and [S III]. The velocity separation between them is ~180 km/s, and the spatial separation is consistent with the two knots seen in the imaging (corresponding to ~8 kpc at this distance), suggesting an interacting pair of galaxies. We acknowledge expert support from the ESO observing staff, particularly Jose Velazquez and Juan Carlos Munoz, in obtaining these observations.