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David Dunlap Observatory Catalogue, known as the DDO or A Catalogue of Dwarf Galaxies, is a catalogue of dwarf galaxies that was compiled by Sidney van den Bergh and published by the David Dunlap Observatory in 1959 (and later expanded in 1966).
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David Dunlap Observatory Catalogue, known as the DDO or A Catalogue of Dwarf Galaxies, is a catalogue of dwarf galaxies that was compiled by Sidney van den Bergh and published by the David Dunlap Observatory in 1959 (and later expanded in 1966).
DDO 3 (also known as NGC 147, PGC 2004, UGC 326, LEDA 2004 or Caldwell 17) is a dwarf spheroidal galaxy which is located in the northern constellation of Cassiopeia, near the border of Andromeda. It is a small satellite galaxy of the famous Messier 31, which is the largest galaxy in the Local Group.
DDO 8 (also known as IC 1613, PGC 3844, UGC 668 or Caldwell 51) is a dwarf irregular galaxy in the constellation Cetus, near the border of Pisces. It was discovered in 1906 by a German astronomer Max Wolf. It is a member of the Local Group.
DDO 69 (also known as Leo A, Leo III, PGC 28868 or UGC 5364) is an irregular galaxy which is located in the constellation of Leo. It is a small satellite galaxy of the Milky Way.
DDO 70 (also known as Sextans B, PGC 28913 or UGC 5373) is an irregular galaxy which is in the constellation of Sextans. It is located 4.44 million light years away from Earth.
DDO 74 (also known as Leo I, Regulus Dwarf, PGC 29488 or UGC 5470) lies approximately 820,000 light years away in the constellation Leo. It is one of the most distant satellite galaxy of the Milky Way. The dwarf spheroidal galaxy is located only 12 arcminutes from Regulus (α Leonis), and the light from Regulus makes the visibility of DDO 74 becomes poor, so it is difficult to be observed.
DDO 75 (also known as Sextans A, PGC 29653 or UGCA 205) is an irregular galaxy located in the constellation Sextans, same as its neighbour DDO 70 (Sextans B). When it is observed from Earth, it appears as a square in shape.
DDO 82 (also known as PGC 30997, UGC 5692, MCG+12-10-045 or CGCG 333-35) is a Magellanic spiral galaxy lies 13 million light years away in the constellation Ursa Major.
DDO 93 (also known as Leo II or PGC 34176) is a dwarf spheroidal galaxy which is located in the constellation of Leo. It was discovered in 1950 by Robert George Harrington and Albert George Wilson. It is one of the satellite galaxies of the Milky Way.
DDO 155 (also known as GR 8, PGC 44491 or UGC 8091) is a dwarf irregular galaxy located approximately 7.9 million light years away from Earth in the constellation of Virgo. A nickname for this galaxy, "Imprint of a Foot", is based on its shape.
DDO 169 (also known as PGC 46127 or UGC 8331) is a dwarf irregular galaxy in the constellation Canes Venatici. It is one of the members of the M51 Group.
DDO 190 (also known as UGC 9240) is a dwarf irregular galaxy which is located in the constellation of Boötes. It is a member of the M94 Group as well.
DDO 199 (also known as Ursa Minor Dwarf, PGC 54074 or UGC 9749) is a dwarf spheroidal galaxy which is located in the northern constellation of Ursa Minor. It was discovered in 1955 by an American astronomer Albert George Wilson. It is a satellite of the Milky Way.
DDO 210 (also known as Aquarius Dwarf or PGC 65367) is a dwarf irregular galaxy in the constellation of Aquarius. It is a member of the Local Group and lies 3.2 ± 0.2 million light years from the Milky Way.
DDO 216 (also known as Pegasus Dwarf Irregular Galaxy, PGC 71538 or UGC 12613) is a dwarf irregular galaxy located in the constellation Pegasus.
A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while compiling his Historia Coelestis Britannica.
The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1019 kilometres), and a total mass of the order of 2×1012 solar masses (4×1042 kg). It consists of two collections of galaxies in a "dumbbell" shape; the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kiloparsecs (3×106 ly; 2×1019 km) and are moving toward one another with a velocity of 123 km/s. The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.
A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.
Leo I is a dwarf spheroidal galaxy in the constellation Leo. At about 820,000 light-years distant, it is a member of the Local Group of galaxies and is thought to be one of the most distant satellites of the Milky Way galaxy. It was discovered in 1950 by Albert George Wilson on photographic plates of the National Geographic Society – Palomar Observatory Sky Survey, which were taken with the 48-inch Schmidt camera at Palomar Observatory.
A dwarf spheroidal galaxy (dSph) is a term in astronomy applied to small, low-luminosity galaxies with very little dust and an older stellar population. They are found in the Local Group as companions to the Milky Way and as systems that are companions to the Andromeda Galaxy (M31). While similar to dwarf elliptical galaxies in appearance and properties such as little to no gas or dust or recent star formation, they are approximately spheroidal in shape and generally have lower luminosity.
The Canis Major Overdensity or Canis Major Dwarf Galaxy is a disputed dwarf irregular galaxy in the Local Group, located in the same part of the sky as the constellation Canis Major.
The Spring Triangle is an astronomical asterism involving an imaginary triangle drawn upon the celestial sphere, with its defining vertices at Arcturus, Spica, and Regulus. This triangle connects the constellations of Boötes, Virgo, and Leo. It is visible in the evening rising in the southeastern sky of the Northern Hemisphere between March and May and setting until August, while at morning rising and setting from November to the end of February.
Ursa Major I Dwarf is a dwarf spheroidal galaxy that orbits the Milky Way galaxy. It was discovered in 2005 within the Ursa Major constellation and is the third least luminous known galaxy.
The Sextans Dwarf Spheroidal is a dwarf spheroidal galaxy that was discovered in 1990 by Mike Irwin as the 8th satellite of the Milky Way, located in the constellation of Sextans. It is also an elliptical galaxy, and displays a redshift because it is receding from the Sun at 224 km/s. The distance to the galaxy is 320,000 light-years and the diameter is 8,400 light-years along its major axis.
The Aquarius Dwarf is a dwarf irregular galaxy, first catalogued in 1959 by the DDO survey. It is located within the boundaries of the constellation of Aquarius. It is a member of the Local Group of galaxies, albeit an extremely isolated one; it is one of only a few known Local Group members for which a past close approach to the Milky Way or Andromeda Galaxy can be ruled out, based on its current location and velocity.
The Milky Way has several smaller galaxies gravitationally bound to it, as part of the Milky Way subgroup, which is part of the local galaxy cluster, the Local Group.
The Cassiopeia Dwarf (also known as Andromeda VII) is a dwarf spheroidal galaxy about 2.45 Mly away in the constellation Cassiopeia. The Cassiopeia Dwarf is part of the Local Group and a satellite galaxy of the Andromeda Galaxy (M31). In the sky, it appears behind the Milky Way's galactic plane, and so it is reddened by 0.194 magnitudes. With a luminosity of 1.8×107 L☉ and a stellar mass of 19.73×106 M☉, it is the brightest and most massive of the Andromeda Galaxy's dwarf spheroidal galaxy satellites. It also has the highest metallicity out of all of them.
Canes Venatici I or CVn I is a dwarf spheroidal galaxy situated in the Canes Venatici constellation and discovered in 2006 in the data obtained by Sloan Digital Sky Survey. It is one of the most distant known satellites of the Milky Way as of 2011 together with Leo I and Leo II. The galaxy is located at a distance of about 220 kpc from the Sun and is moving away from the Sun at a velocity of about 31 km/s. It is classified as a dwarf spheroidal galaxy (dSph) meaning that it has an elliptical shape with the half-light radius of about 550 pc.
Ursa Major II Dwarf is a dwarf spheroidal galaxy situated in the Ursa Major constellation and discovered in 2006 in the data obtained by the Sloan Digital Sky Survey. The galaxy is located approximately 30 kpc from the Sun and moves towards the Sun with the velocity of about 116 km/s. It has an elliptical shape with the half-light radius of about 140 pc.
Constellation families are collections of constellations sharing some defining characteristic, such as proximity on the celestial sphere, common historical origin, or common mythological theme. In the Western tradition, most of the northern constellations stem from Ptolemy's list in the Almagest, and most of the far southern constellations were introduced by sailors and astronomers who traveled to the south in the 16th to 18th centuries. Separate traditions arose in India and China.
Pisces II is a dwarf spheroidal galaxy situated in the Pisces constellation and discovered in 2010 in the data obtained by the Sloan Digital Sky Survey. The galaxy is located at the distance of about 180 kpc (kiloparsecs) from the Sun. It is classified as a dwarf spheroidal galaxy (dSph) meaning that it has an elongated shape with the half-light radius of about 60 pc and ratio of the axis of about 5:3.
Urania's Mirror; or, a view of the Heavens is a set of 32 astronomical star chart cards, first published in November 1824. They are illustrations based on Alexander Jamieson's A Celestial Atlas, but the addition of holes punched in them allow them to be held up to a light to see a depiction of the constellation's stars. They were engraved by Sidney Hall, and were said to be designed by "a lady", but have since been identified as the work of the Reverend Richard Rouse Bloxam, an assistant master at Rugby School.
The Antlia-Sextans Group is a small Galaxy group in the constellations Hydra, Sextans, Antlia and Leo. It is, on average, approximately 4.3 million light-years away from the Milky Way. It is generally considered to be at the very edge of the Local Group and thus part of it. However, other researchers indicate it is an independent Galaxy group, unlikely to be gravitationally bound to the Local Group due to probably lying outside the Local Group's Zero-velocity surface, and thus the nearest Galaxy group to the Local Group rather than a subgroup within the Local Group. Nonetheless—this possible independence may disappear as the Milky Way continues coalescing with Andromeda due to the increased mass, and density thereof, plausibly widening the radius of the Zero-velocity surface of the Local Group.