Prominent institutions in international collaboration network in astronomy and astrophysics

The study explores the international collaboration network consisting of 606 astronomical institutions through the analysis of international coauthored papers published in six journals in astronomy and astrophysics from 2001 to 2009. It shows that the Istituto Nazionale di Astrofisica (INAF) and European Southern Observatory (ESO) are the most notable actors, with the highest values of centrality in the network, while Japan Meteorological Agency (JMA) is the only institution that is completely separated from others. It is observed that national academies in major countries, international organizations, and large observatories are more likely to be the central actors. Yet some world-famous astronomical institutions, such as CfA, NASA, and Caltech, are identified as remarkable actors in the network, they show no strikingly high scores in the centrality measures. Overall, astronomical institutions' network position varies with time; nevertheless, not all of institutions present considerable changes during the investigation periods. While some institutions moved from central to relative peripheral positions, or in the opposite direction, the institutions which are positioned at the very center of the network tend to be stable over time.