The catalogue includes essentially all galaxies north of declination -02°30' and to a limiting diameter of 1.0 arcminute or to a limiting apparent magnitude of 14.5. The primary source of data is the blue prints of the Palomar Observatory Sky Survey (POSS). It also includes galaxies smaller than 1.0 arcminute in diameter but brighter than 14.5 magnitude from the Catalogue of Galaxies and of Clusters of Galaxies (CGCG).
The catalogue contains descriptions of the galaxies and their surrounding areas, plus conventional system classifications and position angles for flattened galaxies. Galaxy diameters are included and the classifications and descriptions are given in such a way as to provide as accurate an account as possible of the appearance of the galaxies on the prints. The accuracy of coordinates is only what is necessary for identifications purposes.
There is an addendum to the catalogue called Uppsala General Catalogue Addendum which is abbreviated as UGCA.
The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced by Halton Arp in 1966. A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the California Institute of Technology. The primary goal of the catalog was to present photographs of examples of the different kinds of peculiar structures found among galaxies.Galaxy
A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million (108) stars to giants with one hundred trillion (1014) stars, each orbiting its galaxy's center of mass.
Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many galaxies are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun. As of March 2016, GN-z11 is the oldest and most distant observed galaxy with a comoving distance of 32 billion light-years from Earth, and observed as it existed just 400 million years after the Big Bang.
Research released in 2016 revised the number of galaxies in the observable universe from a previous estimate of 200 billion (2×1011) to a suggested 2 trillion (2×1012) or more, containing more stars than all the grains of sand on planet Earth. Most of the galaxies are 1,000 to 100,000 parsecs in diameter (approximately 3000 to 300,000 light years) and separated by distances on the order of millions of parsecs (or megaparsecs). For comparison, the Milky Way has a diameter of at least 30,000 parsecs (100,000 LY) and is separated from the Andromeda Galaxy, its nearest large neighbor, by 780,000 parsecs (2.5 million LY).
The space between galaxies is filled with a tenuous gas (the intergalactic medium) having an average density of less than one atom per cubic meter. The majority of galaxies are gravitationally organized into groups, clusters, and superclusters. The Milky Way is part of the Local Group, which is dominated by it and the Andromeda Galaxy and is part of the Virgo Supercluster. At the largest scale, these associations are generally arranged into sheets and filaments surrounded by immense voids. The largest structure of galaxies yet recognised is a cluster of superclusters that has been named Laniakea, which contains the Virgo supercluster.List of astronomical catalogues
An astronomical catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery. Astronomical catalogs are usually the result of an astronomical survey of some kind.List of astronomy acronyms
This is a compilation of initialisms and acronyms commonly used in astronomy. Most are drawn from professional astronomy, and are used quite frequently in scientific publications. A few are frequently used by the general public or by amateur astronomers.
The acronyms listed below were placed into one or more of these categories:
Astrophysics terminology – physics-related acronyms
Catalog – collections of tabulated scientific data
Communications network – any network that functions primarily to communicate with spacecraft rather than performing astronomy
Data – astrophysical data not associated with any single catalog or observing program
Celestial object – acronyms for natural objects in space and for adjectives applied to objects in space
Instrumentation – telescope and other spacecraft equipment, particularly detectors such as imagers and spectrometers
Meeting – meetings that are not named after organizations
Observing program – astronomical programs, often surveys, performed by one or more individuals; may include the groups that perform surveys
Organization – any large private organization, government organization, or company
Person – individual people
Publication – magazines, scientific journals, and similar astronomy-related publications
Software – software excluding catalogued data (which is categorized as "catalog") and scientific images
Spacecraft – any spacecraft except space telescopes
Telescope – ground-based and space telescopes; organizations that operate telescopes (for example, the National Optical Astronomy Observatory (NOAO)) are listed under "organization"Markarian 501
Markarian 501 (or Mrk 501) is a galaxy with a spectrum extending to the highest energy gamma rays. It is a blazar or BL Lac object, which is an active galactic nucleus with a jet that is shooting towards the Earth.
In the very-high-energy gamma ray region of the spectrum, at energies above 1011 eV (0.1 TeV), it is the brightest object in the sky. The object has a redshift of z = 0.034.The galaxy hosting the blazar was studied and catalogued by Benjamin Markarian in 1974. It was first determined to be a very high energy gamma ray emitter in 1996 by J. Quinn at the Whipple Observatory.NGC 1
NGC 1, also occasionally referred to as GC 1, UGC 57, PGC 564 or Holm 2a is an intermediate spiral galaxy of the morphological type Sbc, located approximately 210 to 215 million light-years from the Solar System in the constellation Pegasus. It was discovered on 30 September 1861 by Heinrich d'Arrest.NGC 3367
NGC 3367 is a barred spiral galaxy located in the constellation Leo. It is located at a distance of circa 120 million light years from Earth, which, given its apparent dimensions, means that NGC 3367 is about 85,000 light years across. It was discovered by William Herschel on March 19, 1784.NGC 4278
NGC 4278 is an elliptical galaxy located in the constellation Coma Berenices. It is located at a distance of circa 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4278 is about 65,000 light years across. It was discovered by William Herschel on March 13, 1785. NGC 4278 is part of the Herschel 400 Catalogue and can be found about one and 3/4 of a degree northwest of Gamma Comae Berenices even with a small telescope.NGC 545
NGC 545 is a lenticular galaxy located in the constellation Cetus. It is located at a distance of circa 250 million light years from Earth, which, given its apparent dimensions, means that NGC 545 is about 180,000 light years across. It was discovered by William Herschel on October 1, 1785. It is a member of the Abell 194 galaxy cluster and is included along with NGC 547 in the Atlas of Peculiar Galaxies.
A weak radio source with radio jets has been associated with NGC 545. The short jet crosses the much more prominent jet of NGC 547. Observations of the centre of the galaxy by Hubble Space Telescope didn't reveal the presence of dust or disk features. In the centre of the galaxy is believed to exist a supermassive black hole whose mass is estimated to be about 600 million (108.79) M☉ based on the stellar tidal disruption rate.NGC 545 forms a pair with the equally bright NGC 547, which lies 0.5 arcminutes away. They share a common envelope, however, despite their close position, no tidal features like tails or bridges have been observed. A stellar bridge has been detected between the galaxy pair and NGC 541, which lies 4.5 arcminutes to the southwest (projected distance circa 100 kpc).Observations of the galaxy by the Chandra X-Ray Observatory revealed sharp surface brightness edges on the northeastern part of the galaxy and an extended tail in the soft band. It has been presumed that these are the result of motion of NGC 545 towards the centre of the cluster that has been identified as the location of NGC 547.NGC 547
NGC 547 is an elliptical galaxy and radio galaxy (identified as 3C 40) located in the constellation Cetus. It is located at a distance of circa 220 million light years from Earth, which, given its apparent dimensions, means that NGC 547 is about 120,000 light years across. It was discovered by William Herschel on October 1, 1785. It is a member of the Abell 194 galaxy cluster and is included along with NGC 547 in the Atlas of Peculiar Galaxies.
NGC 547 is a prominent radio galaxy, with two large radio jets of Fanaroff-Riley class I with wide-angle tails. The galaxy is identified as 3C 40B (3C 40A is less prominent and is associated with the nearby galaxy NGC 541), and the source extends for 10 arcminutes in the south-north direction. A small, smooth, dark feature has been observed running across the nucleus in images by the Hubble Space Telescope. Its projected size is 0.3 kpc and its shape suggests it is the near side of a small dust disk.NGC 547 forms a pair with the equally bright NGC 545, which lies 0.5 arcminutes away. They share a common envelope, however, despite their close position, no tidal features like tails or bridges have been observed. A stellar bridge has been detected between the galaxy pair and NGC 541, which lies 4.5 arcminutes to the southwest (projected distance circa 100 kpc).Observations of the galaxy by the Chandra X-Ray Observatory revealed a large very luminous X-ray corona around the galaxy. The gas distribution appears symmetric, without evidence of tails, indicating its relatively low velocity, and thus it has been identified as the centre of the cluster, with NGC 541 and NGC 545 moving towards it.NGC 973
NGC 973 is a giant spiral galaxy located in the constellation Triangulum. It is located at a distance of circa 200 million light years from Earth, which, given its apparent dimensions, means that NGC 973 is about 230,000 light years across. It was discovered by Lewis Swift on October 30, 1885.UGC 12682
UGC 12682 is an irregular galaxy, located in the constellation of Pegasus.
In November 2008, 14-year-old amateur astronomer Caroline Moore from New York became the youngest supernova discoverer when she found SN 2008ha in UGC 12682.UGC 8335
UGC 8335 (Arp 238) is a pair of strongly interacting spiral galaxies. They have been distorted by extreme tidal forces, creating prominent tidal tails and a bridge of gas and stars between the galaxies.UGC 8335 is about 400 million light-years from Earth, in the constellation Ursa Major. It is the 238th object in Halton Arp's Atlas of Peculiar Galaxies.