250407 - ACO 1656 "Coma B" galaxy cluster
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ASTRO:
type=Galaxy cluster const=Coma Berenices mag=N/A dist=321 M ly size=~500,000 ly IMAGE: location=EB Driveway BrtlCls=4 moon=79% WxGb exposure=CMOS OSC: 99x180s (5.0h), G100 EQUIPMENT: camera=ZWO ASI2600MC-Pro optics=ES102 w24mmEP 1.7x (afoc prjctn), F=1238mm, f/12.1 filter=Optolong L-Pro LPS mount=Celestron AVX guiding=Orion 60x240mm, ZWO ASi224MC SOFTWARE: acquisition=Stellarium, NINA, PHD2 processing=PixInsight (RCAstro), Photoshop (RCAstro), LrC |
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The Coma Cluster, formally catalogued as ACO 1656, is a large cluster of galaxies that contains over 1,000 identified galaxies. Together with the Leo Cluster (ACO 1367), the Coma is one of the two (2) major clusters comprising the Coma Supercluster. It is located in, and takes its name from the constellation Coma Berenices.
The Abell catalogue is a catalogue of approximately 4,000 galaxy clusters with at least 30 members having a red shift of z = 0.2 or greater. The original "northern" effort was compiled by American astronomer Dr. George O. Abell of CalTech University in 1958 using plates from the Palomar Observatory Sky Survey ("POSS") immediately after that project was completed, also in 1958. Using a simple magnifying glass, Dr. Abell identified appx 1250 clusters, many of which served as the basis for monumental and on-going studies into the structure of the universe. Then in 1987, Dr. Abell's catalogue was extended to the southern hemisphere after his death by his contemporaries, Harold Corwin and Ronald Olowin. Today, the proper designation for galaxy clusters referenced in this catalogue is ACO, (e.g. - "ACO 1656") in recognition of all 3 of these renowned astronomical scientists.
No. 1656's mean distance from Earth is 321 million light years. Its ten brightest galaxies have apparent magnitudes ranging between 12–14. The central region is dominated by two (2) supergiant elliptical galaxies: NGC 4874 and NGC 4889. The cluster is within a few degrees of the north galactic pole in the sky. Most of the galaxies that inhabit the central portion of the Coma Cluster are elliptical galaxies.
Both dwarf and giant ellipticals are found in abundance in the Coma Cluster. As is usual for clusters of this richness, the population of galaxies is overwhelmingly elliptical, and of the type "S0", with only a few spirals, being younger in age and existing near the outer edges of the cluster. Although many of the individual galaxies in the cluster had been identified previous to Dr. Abell's efforts, the full extent of the cluster was not understood until it was more thoroughly studied in the 1950s by the ACO team at Mount Palomar Observatory.
The Coma Cluster is one of the first places where observed gravitational anomalies were considered to indicate the presence of unobserved mass. In 1933 Swiss Astronomer Fritz Zwicky showed that the galaxies of the Coma Cluster were moving too fast for the cluster to be bound together only by the gravitational forces generated in the visible matter of its galaxies. Though the idea of dark matter would not be accepted for another fifty years, Zwicky wrote that the galaxies must be held together by "dunkle Materie" (dark matter). Today, the existence of dark matter is widely accepted by the scientific community. About 90% of the mass of the Coma cluster is believed to be in the form of dark matter.
Unlike many of the ACO catalogue's entries which are not observable with common amateur astronomical telescopes, this one IS observable using equipment of 20 cm (appx 8 inches) and larger. Imaging is possible with smaller, but still moderately sized equipment of 100mm (appx 4 inches) and larger. The Coma Cluster is one of the most awe inspiring segments of sky available to amateur astronomers today. Once it is seen, it always leaves one with a sense of the true expanse of the universe.
The Abell catalogue is a catalogue of approximately 4,000 galaxy clusters with at least 30 members having a red shift of z = 0.2 or greater. The original "northern" effort was compiled by American astronomer Dr. George O. Abell of CalTech University in 1958 using plates from the Palomar Observatory Sky Survey ("POSS") immediately after that project was completed, also in 1958. Using a simple magnifying glass, Dr. Abell identified appx 1250 clusters, many of which served as the basis for monumental and on-going studies into the structure of the universe. Then in 1987, Dr. Abell's catalogue was extended to the southern hemisphere after his death by his contemporaries, Harold Corwin and Ronald Olowin. Today, the proper designation for galaxy clusters referenced in this catalogue is ACO, (e.g. - "ACO 1656") in recognition of all 3 of these renowned astronomical scientists.
No. 1656's mean distance from Earth is 321 million light years. Its ten brightest galaxies have apparent magnitudes ranging between 12–14. The central region is dominated by two (2) supergiant elliptical galaxies: NGC 4874 and NGC 4889. The cluster is within a few degrees of the north galactic pole in the sky. Most of the galaxies that inhabit the central portion of the Coma Cluster are elliptical galaxies.
Both dwarf and giant ellipticals are found in abundance in the Coma Cluster. As is usual for clusters of this richness, the population of galaxies is overwhelmingly elliptical, and of the type "S0", with only a few spirals, being younger in age and existing near the outer edges of the cluster. Although many of the individual galaxies in the cluster had been identified previous to Dr. Abell's efforts, the full extent of the cluster was not understood until it was more thoroughly studied in the 1950s by the ACO team at Mount Palomar Observatory.
The Coma Cluster is one of the first places where observed gravitational anomalies were considered to indicate the presence of unobserved mass. In 1933 Swiss Astronomer Fritz Zwicky showed that the galaxies of the Coma Cluster were moving too fast for the cluster to be bound together only by the gravitational forces generated in the visible matter of its galaxies. Though the idea of dark matter would not be accepted for another fifty years, Zwicky wrote that the galaxies must be held together by "dunkle Materie" (dark matter). Today, the existence of dark matter is widely accepted by the scientific community. About 90% of the mass of the Coma cluster is believed to be in the form of dark matter.
Unlike many of the ACO catalogue's entries which are not observable with common amateur astronomical telescopes, this one IS observable using equipment of 20 cm (appx 8 inches) and larger. Imaging is possible with smaller, but still moderately sized equipment of 100mm (appx 4 inches) and larger. The Coma Cluster is one of the most awe inspiring segments of sky available to amateur astronomers today. Once it is seen, it always leaves one with a sense of the true expanse of the universe.