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We study the gamma-ray burst GRB 081008 environment by analysing the spectraof its optical afterglow. UVES high resolution spectroscopy of GRB 081008 wassecured ~5 hr after the Swift trigger. Our dataset comprises also three FORS2nearly simultaneous spectra of the same source. The availability of nearlysimultaneous high and low resolution spectra for a GRB afterglow is anextremely rare event. The GRB-Damped Lyman Alpha system at z = 1.9683 showsthat the interstellar medium (ISM) of the host galaxy is constituted by atleast three components which contribute to the line profiles. Component I isthe redmost one, and is 20 km/s and 78 km/s redward component II and III,respectively. We detect several ground state and excited absorption features incomponents I and II. These features have been used to compute the distancesbetween the GRB and the absorbers. Component I is found to be 52 +/- 6 pc awayfrom the GRB, while component II presents few excited transitions and itsdistance is 200+60-80} pc. The hydrogen column density associated to GRB 081008is log NH/cm^-2 = 21.11 +/- 0.10, and the metallicity of the host galaxy is inthe range [X/H] = -1.29 to -0.52. In particular, we found [Fe/H]=-1.19 +/- 0.11and [Zn/H]=-0.52 +/- 0.11 with respect to solar values. This discrepancy can beexplained by the presence of dust in the GRB ISM, given the opposite refractoryproperties of iron and zinc. By deriving the depletion pattern for GRB 081008,we find the optical extinction in the visual band to be AV ~ 0.19 mag. TheCurve of Growth analysis applied to the FORS2 spectra brings column densitiesconsistent at the 3 sigma level to that evaluated from the UVES data using theline fitting procedure. This reflects the low saturation of the detectedGRB\,081008 absorption features.

VLT/UVES and FORS2 spectroscopy of the GRB 081008 afterglow