Motivation

The NRAO Spectral Line Catalog (Splatalogue) is an attempt to collate, rationalize and extend existing spectroscopic resources for use by the astronomical community. The Jet Propulsion Laboratory (JPL) database, the Cologne Database of Molecular Spectroscopy (CDMS) and the Lovas/National Institute of Standards and Technology (NIST) database provide an enormous amount of data collecting the data in all three online databases together generates over 5.8 million transition data entries across 1038 individual entries. As part of the ALMA and EVLA scientific plans, one of the main goals of telescope operations is that each new instrument be easy to use by a novice observer. Specifically, in the ALMA Project Plan v2.0, it is stated clearly that:

"The final major scientific requirement affects the diverse community that will use and benefit from the scientific capabilities that ALMA brings to extend their research endeavors: ALMA should be easy to use by novices and experts alike. Astronomers certainly do not need to be experts in aperture synthesis to use ALMA. Automated image processing will be developed and applied to most ALMA data, with only the more intricate experiments requiring expert intervention."

To that end, we interpret the above statement to also apply to an observer interested in spectral line astrophysics. A spectral line database needs to be available that is descriptive as possible in the way it represents molecular, atomic and recombination line transitions.

Currently, the commonly used databases that are used for this search do not describe transitions in a user-friendly way, and where the catalogs overlap, the descriptions have to be compared and resolved to be consistent. Furthermore, the Lovas/NIST database tabulates only observed interstellar transitions, but it does provide the user with a much better representation of molecular transitions by using a full description of the molecular transition. As such, The North American ALMA Science Center and the Data Services Working Group is dedicated to generating a collated and rationalized database of spectral line frequencies, transitions and line strengths from radio to infrared wavelengths that can be used by the entire astronomical community interested in spectral line astrophysics.