Understanding the Messages in the light- the general-purpose AMDfA atomic/molecular database

We propose a unified atomic/molecular database that will provide the basic information nccdcd to support the spectroscopic capabilities of current and future NASA missions. Chandra, Herschel, HST, XMM Newton, soon SOFIA and JWST, and eventually IXO and follow-on UV missions, will study X-ray, UV, optical, IR, and sub-millimeter spectra produced by cold, warm, and hot gas. The physical state of the gas is determined by ionization processes such as photo, collisional, and charge transfer ionization, the Auger effect, and by recombination processes such as radiative, dielectronic, charge transfer, and three-body recombination. The observed spectrum is determined by level energies, transition probabilities, and collision rates. All ofthese processes must be known for every ion of the abundant elements. A parallel data set is needed for molecules. The proposed database will include all of the relevant processes for the gas detected by these missions. This scope is possible in part because of the parallel development of the spectral synthesis code Cloudy, which requires these data in order to function. We will use modern database technologies and lightweight languages to present a simple user interface allowing access to all types of data through a common API. A web-based top end will allow user interaction and derivation of spectral diagnostics such as temperature and density indicators to be derived from these data.