Galaxy Clusters Database                 The galaxy clusters database contains information on the galaxy clusters listed in Stellarium. The galaxy clusters are listed in the catalogue of galaxy clusters produced by Abell, Corwin and Olowin (ACO catalogue). There are 4076 galaxy clusters from this catalogue along with two others, IC 3574 (in Virgo) and PGC 1520404 (in Gemini). A further 1,074 galaxy clusters in the database are listed in the Southern catalogue (ASO S) along with two others ESO 29-6 (in Tucana) and ESO 152-21 (in Eridanus Australis) . Seven galaxy clusters listed in Stellarium are not actually included in the program. These are:  ACO 1334,  ACO 1984,  ACO 2270,  ACO 3225,  ACO 3574,  ACO 3656 and ACO 3897.              Galaxy Cluster Type The classification of the galaxy clusters follows that of L.P. Bautz and W. W. Morgan. I Clusters which contain a centrally located cD galaxy. I-II Intermediate II Clusters where the brightest galaxy or galaxies are intermediate in appearance between class cD and Virgo-type giant ellipticals. II-III Intermediate III Clusters which contain no dominant galaxies. [ Notes A type-D galaxy is one which has an elliptical-like nucleus surrounded by an extensive envelope. A cD galaxy, which is a subtype of the type-D giant elliptical galaxy, has a large halo of stars which can measure as much as 3 million lightyears in diameter and is located at the centre of a galaxy cluster. The Milky Way is in a group of galaxies called the Local Group which, in turn, is a member of the Virgo Supercluster. A supergiant elliptical galaxy, known as M87, lies at the centre of this cluster. (The distance of M87 is quoted as 60 million lightyears, according to Stellarium  whereas other sources quote the distance as 53.8 million lightyears.)           ] The following file, Galaxy Cluster Types, shows the number of galaxy clusters of a particular type which are in each constellation. Click on the icon to view the file.                                                 Galaxy Cluster Types        Distribution of the Galaxy Clusters           Across the Constellations The following lists show the constellations which have the highest concentration of galaxy clusters (of those listed in Stellarium).        Northern Skies    Southern Skies   1. Ursa Major 327 1. Phoenix      197   2. Cetus 321 2. Grus      167   3. Sculptor 213 3. Tucana      130   4. Hydra 201 4. Centaurus      126   5. Aquarius 193 5. Horologium      116   6. Leo 191 6. Eridanus (Australis)    107   7. Eridanus (Borealis) 177 7. Indus      106   8. Fornax 164   9. Virgo 161 10. Bootes 155 11. Draco 150 12. Pisces 119 13. Pegasus 116 14. Andromeda 205 It is worth pointing out that there are 13 constellations which have no galaxy clusters listed in Stellarium. For a full list of constellations and the number of galaxy clusters in each constellation, see the file “Clusters Analysis Order”. Click on the icon to view the file.  Clusters Analysis Order              Constellation Maps   The following files show the number of galaxy clusters, listed in Stellarium,  which are in each constellation on maps of the constellations.   Click on relevant icon to view the required file.          Northern Skies                     Southern Skies       Summary