Abell catalog

Abell catalog
NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI). "Im · Public domain · source
Name	Abell catalog
Author	George O. Abell
Year	1958
Type	Galaxy cluster catalog
Entries	~4,000 (combined)
Observatory	Palomar Observatory

Abell catalog

The Abell catalog is a seminal compilation of rich galaxy clusters produced from optical survey work at Palomar Observatory and later expanded with southern-sky efforts tied to European Southern Observatory. It influenced programs at institutions such as the Mount Wilson Observatory, Harvard College Observatory, Carnegie Institution for Science, and missions associated with NASA and European Space Agency. The catalog underpinned follow-up studies by teams at California Institute of Technology, Massachusetts Institute of Technology, University of Cambridge, Max Planck Society, and observatories including Kitt Peak National Observatory and Cerro Tololo Inter-American Observatory.

History and development

George O. Abell produced the original northern sample using photographic plates from the Palomar Observatory Sky Survey undertaken with the 48-inch Samuel Oschin telescope; this work connected to contemporaneous surveys at Palomar Mountain and collaborations with researchers at University of California, Los Angeles and Lick Observatory. The southern extension emerged from follow-up programs involving the European Southern Observatory and astronomers active at University of Chile and Australian National University, integrating data comparable to that used in projects by Sloan Digital Sky Survey predecessors and complementing catalog efforts like those at Royal Observatory, Edinburgh. Administratively, the compilation influenced data policies at bodies such as National Science Foundation and inspired later large-scale surveys carried out by Space Telescope Science Institute and ground facilities tied to the National Optical Astronomy Observatory.

Catalogs and contents

The primary compilation exists as an original northern catalog of rich clusters and a later southern supplement; combined, the lists amount to several thousand entries cross-referenced with redshift campaigns led by teams at Harvard-Smithsonian Center for Astrophysics and Institut d'Astrophysique de Paris. Entries were indexed with positions based on the B1950 coordinate system and later cross-matched to J2000 catalogs maintained by services such as the Centre de Données astronomiques de Strasbourg and archives used by the International Astronomical Union. Many cluster records were later tied to radio surveys from National Radio Astronomy Observatory facilities and X-ray sources detected by missions like ROSAT and Chandra X-ray Observatory.

Selection criteria and methodology

Selection relied on visual inspection of glass photographic plates from the Palomar Observatory Sky Survey with richness and concentration thresholds established by Abell for clusters within specific redshift proxies; this methodology paralleled approaches in earlier work at Yerkes Observatory and mirrored selection philosophies in catalogs from Royal Observatory, Greenwich. Richness classes and distance classes were set relative to counts within defined magnitude ranges, a scheme comparable to magnitude-limited selections used by teams at Mount Stromlo Observatory and in projects linked to Smithsonian Institution. Photographic techniques necessitated calibration against plate sensitivity standards developed by groups at Jet Propulsion Laboratory and photometric systems standardized by committees of the International Astronomical Union.

Astronomical significance and applications

The compilation became a cornerstone for studies of large-scale structure pursued by researchers at Princeton University, University of Chicago, California Institute of Technology, and Johns Hopkins University; it provided targets for redshift surveys such as those by the Two-degree Field Galaxy Redshift Survey and the Sloan Digital Sky Survey. The catalog informed cosmological tests involving galaxy cluster mass estimation methods refined at institutions like the Max Planck Institute for Astrophysics and fed X-ray follow-up with XMM-Newton and Chandra X-ray Observatory programs executed by teams at European Space Agency and NASA. It served as a reference for gravitational lensing analyses by groups at University of Oxford, University of Cambridge, and ETH Zurich, and for Sunyaev–Zel'dovich effect observations with facilities operated by Atacama Large Millimeter/submillimeter Array consortia and the South Pole Telescope collaborations.

Notable entries and discoveries

Several well-studied clusters from the list overlap with historically important systems observed at Mount Wilson Observatory and in maps produced by Fritz Zwicky and colleagues; these include massive clusters associated with bright central galaxies investigated at Carnegie Observatories and X-ray luminous systems followed up by ROSAT teams. Subsequent spectroscopic campaigns by researchers at European Southern Observatory and redshift mapping by the Anglo-Australian Observatory revealed substructure and dynamics that shaped models developed at Institute for Advanced Study and by theoreticians at Princeton University. The catalog entries catalyzed multiwavelength programs involving observatories such as Mauna Kea Observatories and space missions coordinated by NASA and European Space Agency science centers.

Limitations and biases

The compilation inherits selection biases tied to photographic-plate depth, plate-to-plate photometric variation addressed by experts at Royal Greenwich Observatory and instrumental systematics recognized in reports from National Optical Astronomy Observatory. Projection effects, a concern highlighted in critiques by researchers at Institute of Astronomy, Cambridge and Observatoire de Paris, produce contamination by line-of-sight superpositions, while richness-based thresholds disadvantage clusters with low surface brightness noted in studies from Max Planck Society groups. Sky coverage is nonuniform, reflecting northern-sky emphasis of Palomar Observatory Sky Survey plates and the later, less-complete southern efforts coordinated with the European Southern Observatory and southern hemisphere institutions such as University of Cape Town.

Category:Astronomical catalogues