About the German ARC node

The German node of the ALMA Regional Center was established as one initiative of the Research Association for Interferometry in North Rhine-Westphalia ("NRW Forschungsverbund Astro-Interferometrie"), which was founded in 2004 in order to strengthen and coordinate the technological, scientific and educational efforts relating to radio and infrared interferometry between the neighboring astronomical groups of Bonn and Cologne. It builds upon a long history of collaboration between the Universities of Bonn, Cologne, and Bochum, and the Max Planck Institute for Radioastronomy in research, education and instrument development. Among the common initiatives have been the "Sonderforschungsbereich 494", the International Max-Planck Research School (IMPRS) for Radio and Infrared Astronomy, and the new Bonn-Cologne Graduate School in Physics and Astronomy. The institutes have been operating the KOSMA, NANTEN2, and APEX submillimeter telescopes, and have developed instruments for these telescopes as well as for Herschel, SOFIA, the LBT and the VLTI. The local Effelsberg 100-meter telescope and strong involvements in global- and mm-VLBI, EVN and LOFAR add to the local expertise in radio interferometry.

In Bonn, the German ARC node provides user support for all levels of ALMA users, who are encouraged to contact the ARC staff via the helpdesk, by phone or email, or visit the node for face-to-face support in an environment with broad (radio-)interferometric expertise. The node serves as a basis for public outreach and a training site that offers specialized courses, schools, and workshops to advance the knowledge of radio-interferometric techniques and science. For example, the training course "Practical Radio Interferometry" has been held once every year since 2008.

In addition to the regular ARC tasks, the German ARC node focusses on several specific areas of expertise, which include:

• The development of advanced data analysis tools


• Polarization calibration and observation optimization


• User training (workshops, tutorials, schools)


• Community development and public outreach

The University of Cologne is responsible for the management, maintainance and upgrade of the Cologne Database for Molecular Spectroscopy (CDMS). This catalog contains predictions on frequency transitions and line parameters such as line intensity and hyperfine emission for atoms and molecules of astrophysical and atmospheric interest.

Together the Cologne and Jet Propulsion catalogues, CDMS and JPL, are the basis for the analysis of all millimeter and sub-mm observations. Both catalogues are using the same model description for the line predictions. In order to combine both catalogues CDMS became one of the molecular data centers within the European project VAMDC (virtual atomic and molecular data centre). Here specific data base tools are developed to make the various databases available to all users. In particular molecular data on collisions and on spectroscopy are united in this project. In the framework of the ARC node, we will maintain and upgrade the database, and provide interfaces and tools for astrophysical users

The CATS program, which among other things develops a versatile fitting engine (MAGIX), was developed within the framework of ASTRONET. The modeling of astronomical observations requires specialized numerical codes and knowledge about how to use them. The program MAGIX provides a framework to easily interface existing codes to an iterating engine that allows automatic minimizations to constrain model parameters and provide error estimates. (M)any models (and, in principle, not only astrophysical models) can be plugged into MAGIX so as to explore their parameter space and find the set of parameter values that best fits observational/experimental data.

The Cologne node will develop a CASA based code that will allow automatic line identification, parameter fitting, and source classification. This code will be using the VAMCD database, and employ the MAGIX fitting engine.