VO Access to BASECOL Database

Astronomical Data Analysis Software and Systems XV ASP Conference Series, Vol. 351, 2006 C. Gabriel, C. Arviset, D. Ponz and E. Solano, eds.

VO Access to BASECOL Database N. Moreau and M.L. Dubernet LERMA-UMR 8112, Paris Observatory, 5 Place Janssen, 92195 Meudon, France Abstract. Basecol is a combination of a website (using PHP and HTML) and a MySQL database concerning molecular ro-vibrational transitions induced by collisions with atoms or molecules. This database has been created in view of the scientific preparation of the Heterodyne Instrument for the Far-Infrared on board the Herschel Space Observatory (HSO). Basecol offers an access to numerical and bibliographic data through various output methods such as ASCII, HTML or VOTable (which is a first step towards a VO compliant system). A web service using Apache Axis has been developed in order to provide a direct access to data for external applications.

1.

Introduction

BASECOL is devoted to collisional ro-vibrational excitation of molecules by colliders such as atom, ion, molecule or electron. The database is composed of several parts: • a status page with information about the needs for astrophysics, the current calculations and experiments being carried out, the possibility to contact the relevant groups • a bibliographic database (papers are read and associated to very precise keywords given back to the user in the query response) • calculated collisional rates • graphical visualization of collisional rates • fitted and analytic functions of some of the collisional rates and the associated coefficients • information on the methods used in the calculation of cross sections and rate coefficients • energy levels of the molecules (coming from spectroscopic databases or used in the theoretical calculations) All tables have output format in HTML or ASCII. The rate coefficients tables are linked to tables containing the correspondence between labelling of states and their quantum numbers and energy levels. They are also linked to tables containing the corresponding fitted coefficients as well as the fitted functions. A graphic interface allows to visualize calculated rate coefficients for any transition, to compare different sets of calculations, and to compare fitted and calculated rate coefficients. 391

392

Moreau & Dubernet

Figure 1.

BASECOL Structure

This database is intended to be useful to astrophysicists and is maintained by physicists. It also provides a link between astrophysicists and physicists interested in carrying on calculations or experiments. 2.

Basecol Structure

Figure 1 gives BASECOL Access structure. There are two ways to access the data contained in the database. The web interface provides a classical website access and information is obtained through a browser, by manually reading and saving files. The site has been developed using PHP4 with an Apache 2 server. The Basecol database itself uses MySQL 4.1.11. The web service access is a direct access point to external applications. It provides a set of methods (described later), that can be accessed directly through a script. This web service has been developed in Java with Axis and Tomcat. However, it is not VO compliant yet. 3.

Basecol Data Output Formats

There are several output formats for data available in Basecol. First, using the web interface, it is possible to choose between three different formats : • HTML format displays data directly in the web browser • Text format: text files have a standard presentation in order to use them easily in codes. • VOTable format Second, there is a web service interface where the only output is the VOTable format. Two different VOTables are provided: the first one containing all data re-

VO Access to BASECOL Database

393

lated to a given collision can be very large and is composed of several elements. VO Tools such as VOPlot or Topcat aren’t able to display multi elements. To solve this problem, a second VOTable composed of a single element is available for rate coefficients only. 4.

Web Service

The Web Service has the following methods: • getCollisions : returns a VOTable containing links to the data that match the request criteria • getCollisionsRates : returns a VOTable containing links to the rate coefficients values that match the request criteria • getColliderList : returns a VOTable containing a list of all the colliders available in the database • getTargetList : returns a VOTable containing a list of all the targets available in the database In order to access these methods, a client must be developed, using a WSDL file we provide (Axis and .Net can generate this type of client automatically). 5.

Matching Between Basecol and Other Molecular Databases

We’re currently developing software to merge CDMS1 , JPL2 and Basecol data (in particular, Basecol doesn’t provide Einstein coefficients). A PHP script is used, it reads JPL and CDMS files, inserts values in a MySQL database in order to improve manipulation of data. This script deals with all the small exceptions that have been used to code quantum numbers. Even if all CDMS files have a similar format, it is necessary to check files individually as some problems occur occasionnally. 6.

Conclusion

Several aspects still need to be developed : • Making the matching function available for all the elements available in our database (which should be available soon) • Some methods can be added to the web service (notably the methods defined by the IVOA for the VO compliant web services) • Giving an access to our data through the future SLAP protocol (which hasn’t been totally defined yet) • Registering this future service in a registry • Completing the collision database Acknowledgments. Basecol is a collaborative project supported by several organizations : Programme National PCMI (Physique Chimie du Milieu Interstellaire), VOFrance, the Scientific Council of Paris Observatory, the LERMA. 1

http://www.ph1.uni-koeln.de/vorhersagen/

2

http://spec.jpl.nasa.gov/