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Dubernet, M. L., Debray, B., Grosjean, A., Bruston, M., Combes, F., Cornille, M., Egret, D., Stéhlé, C., Tchang-Brillet, L., & Zeippen, C. 2003, in ASP Conf. Ser., Vol. 314 Astronomical Data Analysis Software and Systems XIII, eds. F. Ochsenbein, M. Allen, & D. Egret (San Francisco: ASP), 213

Access to Atomic and Molecular Data/Databases in the VO

M.L. Dubernet
LERMA, Observatoire de Paris 5, Place Jules Janssen 92195 Meudon Cedex France

B. Debray, A. Grosjean
Observatoire de Besançon, 41 bis, avenue de l'Observatoire, BP 1615, 25010 Besançon Cedex France

M. Bruston, F. Combes, M. Cornille, D. Egret, C. Stéhlé, L. Tchang-Brillet, C. Zeippen
LERMA, Observatoire de Paris 5, Place Jules Janssen 92195 Meudon Cedex France


Numerical and bibliographical Databases in Atomic and Molecular Physics are essential for both the modelling of various astrophysical media and the interpretation of astrophysical spectra provided by ground or space-based telescopes. We report here on our current project concerning the access to Atomic and Molecular Physics Databases within the Virtual Observatories, addressing the organisation/access of data for specific astrophysical applications and the use of standards for interoperability. As an example we present the current status of a numerical and bibliographical database concerning collisional ro-vibrational excitation rate coefficients of molecules (

1. Presentation

It is important to make atomic and molecular data widely available in interrelating databases with VO projects; this would allow:

Different steps have been identified in order to organise access to atomic and molecular data for astrophysical needs:

  1. identify specific needs for specific applications;
  2. ``validate'' the relevant atomic and molecular data (precision, origin of the data: chain of errors);
  3. get the data into a suitable scientific and technical format;
  4. semantic definition of the data.

Point 1 was started with the organisation of a workshop
(), where physicists and astrophysicists from various areas (solar physics, stars, planets, interstellar medium) met. The following conclusions can be drawn: It is clear that a dedicated organisation of atomic and molecular data would be of the utmost interest. We set up a discussion forum on the subject at

A follow up of the project can be found on

2. A case study: the scientific preparation of HIFI (HSO) and ALMA

In view of the scientific preparation of the HIFI instrument of the Herschel Space Observatory (HSO) ( and of ALMA (, particular needs have been pointed out for:

These questions are addressed respectively by the
Basemol () and (Astrospec) working groups.

2.1 The BASECOL database and related projects

In this framework, different groups have been set up to carry out calculations on collisional ro-vibrational excitation of molecules and to build a related bibliographic and numerical database.
This database, called BASECOL ( is devoted to collisional ro-vibrational excitation of molecules by colliders such as atom, ion, molecule or electron. We have constituted a national working group of molecular physicists involved in the calculations of ro-vibrational cross-sections, in order to ensure the continuity and the quality of the database. We are currently enlarging the collaboration to the international molecular physicists community.

2.2 Current Status and future plans

We are primarily focusing on collisional systems of interest for various astrophysical media. The database is composed of several parts:

For systems of astrophysical interest, we will:

Access is currently available via a classical WEB interface with an interactive query page for the bibliographic database. An interactive access to the collisional rates and cross-sections is underway.

We are also addressing the issue of compatibility of the output of the database within the framework of the Virtual Observatories, in relation both with WEB tools for spectral analysis and with other databases such as the UMIST Database for Astrophysics ( and the Cologne Database for Molecular Spectroscopy  (
We have created a discussion forum at
The BASECOL database will be used both in the modelling of astrophysical objects (such as the model of Photo-Dissociation Regions (PDR) currently available at ( and in the interpretation of observed spectra (CASSIS) for HSO: analysis of observations for the search of new species and the determination of physical conditions.

2.3 Use of standards for interoperability

Definition of data: UCDs

We are currently addressing the semantic definition of the Atomic and Molecular Data, in collaboration with CDS, that is, by defining UCDs
( related to atomic and molecular data. Both the BASECOL database ( and the MOLAT database ( of the Paris Observatory are going to be used to test the UCDs.

The work in progress is the following:

Representing Physics data in VOTable

VOTable ( is an XML standard which was especially designed to transfer astronomical data in tabular form. In molecular physics, the data that are often data cubes (or even ``hypercubes''): for instance the effective collisional rate coefficients as a function of initial and final quantum numbers and temperatures. To be able to represent these data in VOTable, we need some kind of ``projection'' mechanism to place data cube ``slices'' into VOTable'<TABLE>s. Two solutions can be considered:

In both cases, we need a further analyser next to the VOTable parser in order to join data of the same type belonging to either different <FIELD>s or to a given <FIELD>s in successive <TABLE>s.

To gather people interested in these matters and share experiences and questions, a Birds of a Feather session has been organised (Dubernet 2004).



Dubernet, M.L. and Debray, B. , 2004, this volume, 582

Green, S., 1994, VizieR Online Data Catalog, 6051:0+

© Copyright 2004 Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, California 94112, USA
Next: BDB - a database for all types of double stars
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