APED: Astrophysical Plasma Emission Database
Database of atomic transitions used by APEC. It includes line lists, emissivities, observed vs. theoretical wavelengths, and references to the original literature.
The Chandra Emission Line Project is using high-resolution high signal-to-noise HETG and LETG grating spectra of bright stars to check the theoretical line strength and wavelength predictions.
Using APEC on the APED will produce the ATOMDB. See the ATOMDB website for more details on APED.