The 400 sq. deg. Galaxy Cluster Survey

Using archival data of pointed observations from the X-ray satellite ROSAT, the NSI has participated in building the largest (to that depth) catalog of clusters of galaxies (the 400 sq deg catalog) discovered as serendipitous extended X-ray sources.

The catalog can be found at: http://hea-www.harvard.edu/400d/

Galaxy cluster
 

The pointed positions on the sky from where the 400 sq. deg catalog has been created.