9. Conclusions

The main results of our analysis of the spatial distribution of rich clusters and superclusters are:

• we present a new whole-sky catalogue of superclusters of Abell-ACO clusters up to distances z = 0.12 which contains 220 superclusters, 90 of which have been determined for the first time. There are several new very rich superclusters with eight or more member clusters;
• about 2/3 of very rich superclusters are located in the Dominant Supercluster plane that is orthogonal to the Supergalactic plane;
• several tests suggest the presence of a characteristic scale of about Mpc in the distribution of clusters and superclusters of galaxies;
• rich superclusters reside in chains and walls;
• the distribution of superclusters in void walls depends on the supercluster richness;
• the mean space density of Abell-ACO clusters of galaxies, corrected for incompleteness and Galactic extinction, is Mpc.

Acknowledgements

This work was partly supported by the Estonian Science Foundation (grant 182) and by the International Science Foundation (grant LDC 000). JJ would like to thank Division of Astronomy and Physics of Estonian Academy of Sciences for financial support. We thank Drs. V. Müller, E. Saar and D. Tucker for fruitful discussions.