About VALD

The Vienna Atomic Line Database (VALD) is a collection of atomic and molecular transition parameters of astronomical interest. VALD offers tools for selecting subsets of lines for typical astrophysical applications: line identification, preparing for spectroscopic observations, chemical composition and radial velocity measurements, model atmosphere calculations etc.

This web portal is the main user interface to VALD and it offers full functionality of the extraction tools and flexibility of data access. Noteworthy concepts that may help you using VALD in the most efficient way:

• VALD extraction tools are constructed for intelligent selection of data relevant for specific astronomical problem. For background informatio on each extraction method, see the documentation wiki.
• Bulk data transfer via remote access is highly inefficient. For massive data extractions (e.g. for computing opacity tables) you should consider hosting a mirror site. Contact the VALD administrator if you are interested.
• VALD is regularly updated with critically evaluated data sets. The VALD project team experts investigate the statistical properties of the data, extensively compare the results obtained with different data sources, and establish the quality rating for each new source which is a basis for data selection. This portal offers you a possibility to create and save an alternative ranking table that would also ensures reproducibility of the extraction.
• VALD data access is free but requires registration. Registration helps us rejecting spam, collecting statistics and informing you about updates. We do not share your registration information with anyone.