The Catalog of Open Cluster Data (COCD) is a result of studies of the wide neighborhoods of 513 open clusters and 7 compact associations carried out in the high-precision homogeneous All-Sky Compiled Catalog of 2.5 Million Stars (ASCC-2.5, Kharchenko 2001, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/280">CDS Cat. <I/280></a>). On the basis of data on about 33,000 possible members (including about 10,000 most probable ones) and homogeneous methods of cluster parameter determination, the angular sizes of cluster cores and coronae, cluster heliocentric distances, mean proper motions, mean radial velocities and ages were established and collected in the COCD. These include cluster distances for 200 clusters, average cluster radial velocities for 94 clusters, and cluster ages for 195 clusters derived for the first time. Clusters in the catalogue are sequenced in their Right Ascension J2000 order. The Open Cluster Diagrams Atlas (OCDA) presents a set of open cluster diagrams used for the determination of parameters of the 513 open clusters and 7 compact associations, and is intended to illustrate the quality of the constructed cluster membership (Kharchenko et al. 2004, CDS Cat. <J/AN/325/740>), and the accuracy of the derived cluster parameters. Every diagram presents relation between various stellar data from the ASCC-2.5 in the area of the specific cluster. There are five diagrams provided for every cluster in the Atlas: the area map, the density profile, the vector point diagram, the magnitude equation diagram and the color-magnitude diagram. The OCDA PostScript plots (one file per cluster) are available as a remote data product for entries in this table. This table was created by the HEASARC in May 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/438/1163">CDS Catalog J/A+A/438/1163</a> files cocd.dat and notes.dat. This is a service provided by NASA HEASARC .