VALD-2: Progress of the Vienna Atomic Line Data Base

We describe the updated version of the "Vienna atomic Line Data Base" (VALD : Piskunov et al. 1995) which represents a considerable improvement over th e first installation from 1994. The original line lists have been complemen ted with critically evaluated data obtained from experimental measurements and theoretical calculations which are necessary for computing state-of-the -art line opacities in stellar atmospheres: as well as for synthesizing spe ctra for high precision analyses. In this paper. we present new and improve d data sets for neutral species and ions of Si, P, Sc, Ti, V, Cr, Mn, Fe, C o, Ni, Cu, Zn, Y, Zr, Ru, Xe, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Y b, Lu, Re, Pt, Au, Hg, and Pb. For some species data are available in VALD for the first time. We explain our choice of quality rankings by reviewing the literature for the new data and by comparison with source lists include d into VALD. For some cases, we produced new line data by weighted averagin g of data from different sources with individual error estimates in order t o increase the reliability of VALD line lists. Software modifications allow remote users of VALD to specify individual ext raction parameters as an alternative to the default settings of the VALD te am and to have direct control over the quality ranking of line data. A Worl d-Wide-Web interface is described which provides easy access to all new fea tures. To simplify proper crediting of all authors of atomic data, VALD now includ es a compilation of all publications used in each type of reply. Finally, we briefly discuss the future roadmap of VALD developments, includ ing the incorporation of molecular transitions and integration with externa l data bases.