The Vienna Atomic Line Data Base – a Status Report

Atomic transition parameters are of fundamental importance for many aspects of astrophysical research. But this information is spread over an enormous variety of publications in the fields of, e.g., applied and atomic physics, chemistry, and astronomy. Moreover, they differ in parameters listed and physical units used, as well as in their relative and absolute accuracy. This unfortunate situation led us to create a set of both critically evaluated and more homogeneous lists of astrophysically important atomic transition parameters and of supporting extraction software. This new data base is called the "Vienna Atomic Line Data Base" (VALD) and contains about 600000 entries for spectral lines with measured energy levels. VALD includes tools for extracting data and references which are particularly suitable for astrophysical applications such as spectrum synthesis and model atmosphere calculations. They are described in papers by Piskunov et al (1995) and Kupka et al (1999). We describe in this paper the structure of VALD, present a summary of all available data sets, explain our ranking procedure, in particular for the case of recent data on Fe I and Fe II, and comment briefly on the specific retrieval tools. The electronic-mail interface VALD–EMS allows remote access to VALD and is now extended by the WWW interfaces: http://www.astro.univie.ac.at/~vald and http://www.astro.uu.se/~vald