2 Data

The spectra of QSO 0347-3819 (V=17.3, $z_{\rm em} = 3.23$) were obtained during the Commissioning of the Ultraviolet-Visual Echelle Spectrograph (UVES) on the VLT 8.2 m Kueyen telescope at Paranal, in 1999. The instrument is described in D'Odorico et al. (2000). Two exposures of 4500 s each, covering the spectral range from 3650 to 4900 Å and from 6700 to 10000 Å were obtained with a resolution of $\approx$6.9 km s^-1 and $\approx$5.7 kms^-1 respectively. The individual spectra were reduced using the UVES data reduction pipeline implemented in the ESO MIDAS package. The final spectrum reaches a S/N varying from 20 to 35.

QSO 0347-3819 shows a damped Ly$\alpha$ system at $z_{\rm abs} = 3.025$ which has been studied in detail by Centurion et al. (1998), Ledoux et al. (1998) and from HIRES-Keck observations by Prochaska & Wolfe (1999). The UVES observations however provide the first high-quality data in the UV ( $\lambda < 4900$ Å) and in the near-IR ( $\lambda > 6700$ Å). They allow the abundance measurements of new features such as O, P, Ar and Zn, in addition to the N, S, Si and Fe abundances measured in the previous studies. Full abundance analysis of the DLA system at $z_{\rm abs} = 3.025$ will be presented in a future paper. Here we focus on the deuterium detection and the D/H ratio measurement.

 

 

Table 1: Column densities

Comp	$z_{\rm abs}$	Ident	$\log N$	b
			[cm-2]	[km s-1]
2...	3.024637	H I	20.13 $\pm$ 0.08	21.5 $\pm$ 0.4
		D I	15.48 $\pm$ 0.08	14.1 $\pm$ 0.5
3...	3.024856	H I	20.43 $\pm$ 0.10	23.0 $\pm$ 2.0
		D I	15.78 $\pm$ 0.11	16.2 $\pm$ 3.0
7...	3.025659	H I	19.35 $\pm$ 0.05	14.7 $\pm$ 0.4