A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived outline or pattern, typically representing an animal, mythological person or creature, or an inanimate object. The origins of the earliest constellations likely go back to prehistory. People used them to relate stories of their beliefs, experiences, creation, or mythology. Different cultures and countries adopted their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. The recognition of constellations has changed significantly over time. Many have changed in size or shape. Some became popular, only to drop into obscurity.
Introduction
Constellation
Constellation | Introduction
Sorry. I cannot find the answer based on the context. Sorry. I cannot find the answer based on the context. A deep-sky object is any astronomical object that is not an individual star or Solar System object. The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects. Hydrus contains only faint deep-sky objects. Sorry. I cannot find the answer based on the context.
what is hydrus?
user
Small constellation in the deep southern sky.
assistant
what are its characteristics?
user
Irregular in shape and its tail has been shortened to make space for this last constellation he had drawn up.
assistant
name a few stars in the constellation?
user
Beta Hydri, Alpha Hydri, etc.
assistant
where did the second star get its name from?
user
Chinese system
assistant
who decribed the constellation for the first time?
user
Goes back to prehistory.
assistant
what does deep sky objects mean in the context of the constellation?
user
However, the remnant itself was not discovered until 1731, when John Bevis found it.
Taurus (constellation) | Deep-sky objects
The cluster, 6200 light-years from Earth and 20 light-years in diameter, contains approximately 3000 stars, making it a particularly rich cluster. It is 220 million years old.
Scutum (constellation) | Deep sky objects
The smaller galaxy in the collision is now incorporated into the core, after moving from a distance of 250,000 light-years. The shock waves from the collision sparked extensive star formation in the outer ring.
Sculptor (constellation) | Deep sky objects
It was discovered in 2000 by Joselino Vasquez, and confirmed by a team of astronomers under the leadership of R. J. Hurt at 2MASS.
Sagittarius (constellation) | Other deep sky objects
The galaxies in the constellation are faint. IC 4633 is a very faint spiral galaxy surrounded by a vast amount of Milky Way line-of-sight integrated flux nebulae—large faint clouds thought to be lit by large numbers of stars.
Apus | Deep-sky objects
It is also more distant, at 8200 light-years from Earth. Its most prominent member is actually a closer, superimposed double star; it consists of a 7th-magnitude primary and 10th-magnitude secondary.
Cassiopeia (constellation) | Deep-sky objects
The ancient Chinese interpreted the object as a ghost or demon riding in a carriage, calling it a "cloud of pollen blown from under willow catkins." The smaller, denser open cluster Messier 67 can also be found in Cancer, 2600 light-years from Earth. It has an area of approximately 0.5 square degrees, the size of the full Moon. It contains approximately 200 stars, the brightest of which are of the tenth magnitude. QSO J0842+1835 is a quasar used to measure the speed of gravity in VLBI experiment conducted by Edward Fomalont and Sergei Kopeikin in September 2002.
Cancer (constellation) | Deep-sky objects
Its shape has been described as "triangular"; this 80-star cluster is unusually large, more than half a degree in diameter, larger than the diameter of the full Moon.
Hydra (constellation) | Deep-sky objects
In the northern part of the constellation to the northwest of the Pleiades lies the Crystal Ball Nebula, known by its catalogue designation of NGC 1514. This planetary nebula is of historical interest following its discovery by German-born English astronomer William Herschel in 1790. Prior to that time, astronomers had assumed that nebulae were simply unresolved groups of stars. However, Herschel could clearly resolve a star at the center of the nebula that was surrounded by a nebulous cloud of some type. In 1864, English astronomer William Huggins used the spectrum of this nebula to deduce that the nebula is a luminous gas, rather than stars.
Taurus (constellation) | Deep-sky objects
A deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies. This distinction is practical and technical, implying a variety of instruments and techniques appropriate to observation, and does not distinguish the nature of the object itself.
Deep-sky object | Introduction
It is also very large, with an apparent diameter of over 0.25 degrees, half the size of the full moon; its physical diameter is more than 100 light-years. Individual stars in M13 are resolvable in a small amateur telescope.
Hercules (constellation) | Deep-sky objects
Due to its location straddling the Milky Way, this constellation contains many deep-sky objects such as the open clusters Messier 6 (the Butterfly Cluster) and Messier 7 (the Ptolemy Cluster), NGC 6231 (by ζ² Sco), and the globular clusters Messier 4 and Messier 80. Messier 80 (NGC 6093) is a globular cluster of magnitude 7.3, 33,000 light-years from Earth. It is a compact Shapley class II cluster; the classification indicates that it is highly concentrated and dense at its nucleus. M80 was discovered in 1781 by Charles Messier. It was the site of a rare discovery in 1860 when Arthur von Auwers discovered the nova T Scorpii.
Scorpius | Deep-sky objects
Its extremely low metallicity indicates it is very old—one of the oldest clusters in the Milky Way. Extending south from it is the Dark Doodad Nebula, resembling a dark L-shaped river through a bright field of stars. Another dark nebula in the constellation is BHR 71.
Musca | Deep-sky objects
The tail of stars drawn off the Tadpole Galaxy appears blue because the gravitational interaction disturbed clouds of gas and sparked star formation.
Draco (constellation) | Deep-sky objects
It is a large nebula, 55 by 18 arcminutes, that possesses several stars around magnitude 13. These stars have been dimmed by up to 8 magnitudes by its dust clouds.
Corona Australis | Deep sky objects
Larger still is El Gordo, or officially ACT-CL J0102-4915, whose discovery was announced in 2012. Located around 7.2 billion light years away, it is composed of two subclusters in the process of colliding, resulting in the spewing out of hot gas, seen in X-rays and infrared images.
Phoenix (constellation) | Deep-sky objects
Classifying non-stellar astronomical objects began soon after the invention of the telescope. One of the earliest comprehensive lists was Charles Messier's 1774 Messier catalog, which included 103 ""nebulae"" and other faint fuzzy objects he considered a nuisance since they could be mistaken for comets, the objects he was actually searching for. As telescopes improved these faint nebulae would be broken into more descriptive scientific classifications such as interstellar clouds, star clusters, and galaxies. ""Deep-sky object"", as an astronomical classification for these objects, has its origins in the modern field of amateur astronomy. The origin of the term is unknown but it was popularized by "Sky & Telescope" magazine's "Deep-Sky Wonders" column, which premiered in their first edition in 1941, created by Leland S.
Deep-sky object | Origins and classification
North of the Equator, this period stretches from February to May. Ptolemy described the Beehive Cluster as "the nebulous mass in the breast of Cancer." It was one of the first objects Galileo observed with his telescope in 1609, spotting 40 stars in the cluster. Today, there are about 1010 high-probability members, most of them (68 percent) red dwarfs. The Greeks and Romans identified the nebulous object as a manger from which two donkeys, represented by the neighbouring stars [1213] Asellus Borealis and [1210] Asellus Australis, were eating. The stars represent the donkeys that the god Dionysus and his tutor Silenus rode in the war against the Titans.
Cancer (constellation) | Deep-sky objects
A degree to the northwest of ζ Tauri is the Crab Nebula (M1), a supernova remnant. This expanding nebula was created by a Type II supernova explosion, which was seen from Earth on July 4, 1054. It was bright enough to be observed during the day and is mentioned in Chinese historical texts. At its peak, the supernova reached magnitude −4, but the nebula is currently magnitude 8.4 and requires a telescope to observe. North American peoples also observed the supernova, as evidenced from a painting on a New Mexican canyon and various pieces of pottery that depict the event.
Taurus (constellation) | Deep-sky objects
The remnant contains the Vela Pulsar, the first pulsar to be identified optically. Nearby is NGC 2736, also known as the Pencil Nebula. HH-47 is a Herbig-Haro Object, a young star around 1,400 light-years from the Sun that is ejecting material at tremendous speed (up to a million kilometres per hour) into its surrounds. This material glows as it hits surrounding gas.
Vela (constellation) | Deep-sky objects
Hydrus contains only faint deep-sky objects. IC 1717 was a deep-sky object discovered by the Danish astronomer John Louis Emil Dreyer in the late 19th century. The object at the coordinate Dreyer observed is no longer there, and is now a mystery. It was very likely to have been a faint comet. PGC 6240, known as the White Rose Galaxy, is a giant spiral galaxy surrounded by shells resembling rose petals, located around 345 million light years from the Solar System. Unusually, it has cohorts of globular clusters of three distinct ages suggesting bouts of post-starburst formation following a merger with another galaxy.
Hydrus | Deep-sky objects
The smaller star remained in orbit inside the larger, whose rotation speed increased greatly, resulting in it flinging its outer layers off into space, forming a ring with knots of bright gas formed from clumps of stellar material. Both nebulae are around from Earth.
Sagitta | Deep-sky objects
It is very similar in size and shape to the Milky Way and is located 25 million light-years from Earth. In its core, NGC 2903 has many "hotspots", which have been found to be near regions of star formation. The star formation in this region is thought to be due to the presence of the dusty bar, which sends shock waves through its rotation to an area with a diameter of 2,000 light-years. The outskirts of the galaxy have many young open clusters.
Leo (constellation) | Deep-sky objects
The planetary nebula NGC 2438 is superimposed; it is approximately 2900 light-years from Earth. M46 is classified as a Shapley class f and a Trumpler class III 2 m cluster. This means that it is a rich cluster that appears distinct from the star field. However, it is not at its center. The cluster's stars, numbering between 50 and 100, have a moderate range in brightness.
Puppis | Deep-sky objects
Its outer arms have a high number of Cepheid variables, which are used as standard candles to determine astronomical distances. Because of this, astronomers used several Cepheid variables in NGC 4639 to calibrate type 1a supernovae as standard candles for more distant galaxies.
Virgo (constellation) | Deep-sky objects
Most of the cloud is located in the neighbouring constellation Tucana.
Hydrus | Deep-sky objects
It is the third nearest to the Local Group after the Virgo Cluster and the Fornax Cluster. The cluster's distance from earth is to Located in the southeastern corner of the constellation, it boasts the giant elliptical galaxies NGC 3268 and NGC 3258 as the main members of a southern and northern subgroup respectively, and contains around 234 galaxies in total.
Antlia | Deep-sky objects
First discovered by Édouard Stephan, a Frenchman, in 1877, the Quintet is unique for its interacting galaxies. Two of the galaxies in the middle of the group have clearly begun to collide, sparking massive bursts of star formation and drawing off long "tails" of stars. Astronomers have predicted that all five galaxies may eventually merge into one large elliptical galaxy.
Pegasus (constellation) | Deep-sky objects
Mensa contains several described open clusters, most of which can be only be clearly observed from large telescopes. PKS 0637-752 is a distant quasar with a calculated redshift of z = 0.651. It was chosen as the first target of the then newly-operational Chandra X-Ray Observatory in 1999. The resulting images revealed a gas jet approximately 330,000 light-years long. It is visible at radio, optical and x-ray wavelengths.
Mensa (constellation) | Deep-sky objects
Although not a large constellation, Scutum contains several open clusters, as well as a globular cluster and a planetary nebula. The two best known deep sky objects in Scutum are M11 (the Wild Duck Cluster) and the open cluster M26 (NGC 6694). The globular cluster NGC 6712 and the planetary nebula IC 1295 can be found in the eastern part of the constellation, only 24 arcminutes apart. The most prominent open cluster in Scutum is the Wild Duck Cluster, M11. It was named by William Henry Smyth in 1844 for its resemblance in the eyepiece to a flock of ducks in flight.
Scutum (constellation) | Deep sky objects
Because Dorado contains part of the Large Magellanic Cloud, it is rich in deep sky objects. The Large Magellanic Cloud, 25,000 light-years in diameter, is a satellite galaxy of the Milky Way Galaxy, located at a distance of 179,000 light-years. It has been deformed by its gravitational interactions with the larger Milky Way. In 1987, it became host to SN 1987A, the first supernova of 1987 and the closest since 1604. This 25,000-light-year-wide galaxy contains over 10,000 million stars. All coordinates given are for Epoch J2000.0.
Dorado | Deep-sky objects
The Milky Way covers much of the constellation's area. Of the deep-sky objects in Apus, there are two prominent globular clusters—NGC 6101 and IC 4499—and a large faint nebula that covers several degrees east of Beta and Gamma Apodis. NGC 6101 is a globular cluster of apparent magnitude 9.2 located around 50,000 light-years distant from Earth, which is around 160 light-years across. Around 13 billion years old, it contains a high concentration of massive bright stars known as blue stragglers, thought to be the result of two stars merging. IC 4499 is a loose globular cluster in the medium-far galactic halo; its apparent magnitude is 10.6.
Apus | Deep-sky objects
The Milky Way is at its densest near Sagittarius, as this is where the galactic center lies. As a result, Sagittarius contains many star clusters and nebulae.
Sagittarius (constellation) | Deep-sky objects
A barred spiral galaxy, its distorted shape is probably due to a past collision, possibly with the nearby NGC 4027A. NGC 4782 and NGC 4783 are a pair of merging elliptical galaxies in the northeastern part of the constellation, around 200 million light-years distant.
Corvus (constellation) | Deep-sky objects
One of deep-sky objects in Draco is the Cat's Eye Nebula (NGC 6543), a planetary nebula approximately 3,000 light-years away that was discovered by English astronomer William Herschel in 1786. It is 9th magnitude and was named for its appearance in the Hubble Space Telescope, though it appears as a fuzzy blue-green disk in an amateur telescope. NGC 6543 has a very complex shape due to gravitational interactions between the components of the multiple star at its center, the progenitor of the nebula approximately 1,000 years ago. It is located 9.6 arcminutes away from the north ecliptic pole to the west-northwest.
Draco (constellation) | Deep-sky objects
Copeland, written for the majority of its run by Walter Scott Houston, and currently penned by Sue French. Houston's columns, and later book compilations of those columns, helped popularize the term, each month giving the reader a guided tour of a small part of the sky highlighting well known and lesser known objects for binoculars and small telescopes.
Deep-sky object | Origins and classification
The name originates from the huge tidal tails that come off the ends of the two galaxies, formed because of the spiral galaxies' original rotation. Both original galaxies were spiral galaxies and are now experiencing extensive star formation due to the interaction of gas clouds. The galaxies are 45 million light-years from Earth and each has multiple ultraluminous X-ray sources, the source of which is unknown. Astronomers theorize that they may be a rare type of x-ray emitting binary stars or intermediate-mass black holes. The Antennae Galaxies appear in a telescope at the 10th magnitude. SN 2004gt was a type Ic supernova that erupted on December 12, 2004.
Corvus (constellation) | Deep-sky objects
Its rich Milky Way star field means many modestly deep-sky objects. NGC 6891 is a planetary nebula of magnitude 10.5; another is NGC 6905 or the Blue Flash nebula. NGC 6934 is a globular cluster of magnitude 9.75. At a distance of about 185,000 light-years, the globular cluster NGC 7006 is at the outer reaches of the galaxy. It is also fairly dim at magnitude 11.5.
Delphinus | Deep-sky objects
The Dumbbell Nebula (M27), is a large, bright planetary nebula which was discovered by the French astronomer Charles Messier in 1764 as the very first object of its kind. It can be seen with good binoculars in a dark sky location, appearing as a dimly glowing disk approximately 6 arcminutes in diameter. A telescope reveals its double-lobed shape, similar to that of an hourglass. Brocchi's Cluster (Collinder 399) is an asterism formerly thought to be an open cluster. It is also called "the Coathanger" because of its distinctive star pattern when viewed with binoculars or a low power telescope. NGC 7052 is an elliptical galaxy in Vulpecula at a distance of 214 million light-years from Earth.
Vulpecula | Deep-sky objects
The Horologium-Reticulum Supercluster is a galaxy supercluster, second in size only to the Shapley Supercluster in the local universe (anything within 200 mpc of Earth). It contains over 20 Abell galaxy clusters and covers more than 100 deg of the sky, centered roughly at equatorial coordinates α = , δ = .
Horologium (constellation) | Deep-sky objects
Carina also contains the naked-eye globular cluster NGC 2808. Epsilon Carinae and Upsilon Carinae are double stars visible in small telescopes.
Carina (constellation) | Deep-sky objects
Hanging from Orion's belt is his sword, consisting of the multiple stars θ1 and θ2 Orionis, called the Trapezium and the Orion Nebula (M42). This is a spectacular object that can be clearly identified with the naked eye as something other than a star. Using binoculars, its clouds of nascent stars, luminous gas, and dust can be observed. The Trapezium cluster has many newborn stars, including several brown dwarfs, all of which are at an approximate distance of 1,500 light-years. Named for the four bright stars that form a trapezoid, it is largely illuminated by the brightest stars, which are only a few hundred thousand years old.
Orion (constellation) | Deep-sky objects
A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived outline or pattern, typically representing an animal, mythological person or creature, or an inanimate object. The origins of the earliest constellations likely go back to prehistory. People used them to relate stories of their beliefs, experiences, creation, or mythology. Different cultures and countries adopted their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. The recognition of constellations has changed significantly over time. Many have changed in size or shape. Some became popular, only to drop into obscurity.
Constellation | Introduction
GOODS-S 29323 is located in the constellation Fornax, at RA: 03h 32m 28s and Dec: –27° 48′ 30″
Great Observatories Origins Deep Survey | Instruments
Libra is home to one bright globular cluster, NGC 5897. It is a loose cluster, 50,000 light-years from Earth; it is fairly large and has an integrated magnitude of 9. IC 1059 is a galaxy in the constellation Libra.
Libra (constellation) | Deep-sky objects
The distance he found was far greater than the size of the Milky Way, which led him to the conclusion that many similar objects were "island universes" on their own. Hubble originally estimated that the Andromeda Galaxy was 900,000 light-years away, but Ernst Öpik's estimate in 1925 put the distance closer to 1.5 million light-years.
Andromeda (constellation) | Deep-sky objects
The manuscript reflects the clarity of the night sky in the Middle Ages, a time without modern air pollution or light pollution. Medieval people generally had a much greater knowledge of the constellations than modern people do today.
Leiden Aratea | Scientific Context
The 13th magnitude planetary nebula PN G243-37.1 is also in the eastern regions of the constellation. It is one of only a few planetary nebulae found in the galactic halo, being light-years below the Milky Way's 1000 light-year-thick disk.
Caelum | Deep-sky objects
3C 48 was the first quasar ever to be observed, although its true identity was not uncovered until after that of 3C 273 in 1963. It has an apparent magnitude of 16.2 and is located about 5 degrees northwest of Alpha Trianguli.
Triangulum | Deep-sky objects
The constellation also contains a spiral galaxy, NGC 1511, which lies edge on to observers on Earth and is readily viewed in amateur telescopes. Located mostly in Dorado, the Large Magellanic Cloud extends into Hydrus. The globular cluster NGC 1466 is an outlying component of the galaxy, and contains many RR Lyrae-type variable stars. It has a magnitude of 11.59 and is thought to be over 12 billion years old. Two stars, HD 24188 of magnitude 6.3 and HD 24115 of magnitude 9.0, lie nearby in its foreground. NGC 602 is composed of an emission nebula and a young, bright open cluster of stars that is an outlying component on the eastern edge of the Small Magellanic Cloud, a satellite galaxy to the Milky Way.
Hydrus | Deep-sky objects
3100 light-years from Earth, more than 30 stars are visible in a diameter of 8 arcseconds. The prominent star in the north of the cluster has a golden color, whereas the stars in the south of the cluster appear orange. Collinder 421 appears to be embedded in nebulosity, which extends past the cluster's borders to its west. Berkeley 90 is a smaller open cluster, with a diameter of 5 arcminutes. More than 16 members appear in an amateur telescope.
Cygnus (constellation) | Deep-sky objects
Hydra contains three Messier objects. M83, also known as the Southern Pinwheel Galaxy, is located on the border of Hydra and Centaurus, M68 is a globular cluster near M83, and M48 is an open star cluster in the western end of the serpent. NGC 3242 is a planetary nebula of magnitude 7.5, 1400 light-years from Earth. Discovered in 1785 by William Herschel, it has earned the nickname "Ghost of Jupiter" because of its striking resemblance to the giant planet. Its blue-green disk is visible in small telescopes and its halo is visible in larger instruments. M48 (NGC 2548) is an open cluster that is visible to the naked eye under dark skies.
Hydra (constellation) | Deep-sky objects
NGC 1535 is a small blue-gray planetary nebula visible in small amateur telescopes, with a disk visible in large amateur instruments. 2000 light-years away, it is of the 9th magnitude. IC 2118 is a faint reflection nebula believed to be an ancient supernova remnant or gas cloud illuminated by nearby supergiant star Rigel in Orion. Eridanus contains the galaxies NGC 1232, NGC 1234, NGC 1291 and NGC 1300, a grand design barred spiral galaxy.
Eridanus (constellation) | Deep-sky objects
Leo contains many bright galaxies; Messier 65, Messier 66, Messier 95, Messier 96, Messier 105, and NGC 3628 are the most famous, the first two being part of the Leo Triplet. The Leo Ring, a cloud of hydrogen, helium gas, is found in orbit of two galaxies found within this constellation.M66 is a spiral galaxy that is part of the Leo Triplet, whose other two members are M65 and NGC 3628. It is at a distance of 37 million light-years and has a somewhat distorted shape due to gravitational interactions with the other members of the Triplet, which are pulling stars away from M66.
Leo (constellation) | Deep-sky objects
M37's Trumpler class is given as both I 2 r and II 1 r. The stars visible in a telescope range in magnitude from 9.0 to 13.0; there are two 9th magnitude stars in the center of the cluster and an east to west chain of 10th and 11th magnitude stars.
Auriga (constellation) | Deep-sky objects
Because of its position away from the galactic plane, the majority of deep-sky objects in Aquarius are galaxies, globular clusters, and planetary nebulae. Aquarius contains three deep sky objects that are in the Messier catalog: the globular clusters Messier 2, Messier 72, and the open cluster Messier 73. Two well-known planetary nebulae are also located in Aquarius: the Saturn Nebula (NGC 7009), to the southeast of μ Aquarii; and the famous Helix Nebula (NGC 7293), southwest of δ Aquarii. M2, also catalogued as NGC 7089, is a rich globular cluster located approximately 37,000 light-years from Earth. At magnitude 6.5, it is viewable in small-aperture instruments, but a 100 mm aperture telescope is needed to resolve any stars.
Aquarius (constellation) | Deep sky objects
NGC 1851 a globular cluster in Columba appears at 7th magnitude in a far part of our galaxy as is 39,000 light-years away - it is resolvable south of at greatest latitude +40°N in medium-sized amateur telescopes (under good conditions).
Columba (constellation) | Deep-sky objects
It has a black hole of around a million solar masses at its centre. Known as a starburst galaxy due to very high rates of star formation, it has a bluish colour due to the huge numbers of young stars within it.
Pyxis | Deep sky objects
Although Ara lies close to the heart of the Milky Way, two spiral galaxies (NGC 6215 and NGC 6221) are visible near star Eta Arae.
Ara (constellation) | Deep-sky objects
Due to its small size and its distance from the plane of the Milky Way, Equuleus contains no notable deep sky objects. Some very faint galaxies between magnitudes 13 and 15 include NGC 7015, NGC 7040, NGC 7045 and NGC 7046.
Equuleus | Deep-sky objects
In 1999, a nearby open cluster was discovered centered on the star η Chamaeleontis. The cluster, known as either the Eta Chamaeleontis cluster or Mamajek 1, is 8 million years old, and lies 316 light years from Earth. The constellation contains a number of molecular clouds (the Chamaeleon dark clouds) that are forming low-mass T Tauri stars. The cloud complex lies some 400 to 600 light years from Earth, and contains tens of thousands of solar masses of gas and dust. The most prominent cluster of T Tauri stars and young B-type stars are in the Chamaeleon I cloud, and are associated with the reflection nebula IC 2631.
Chamaeleon | Deep-sky objects
Both lie more than 7,000 light-years from Earth and are several hundred light-years apart. Both clusters are of approximately magnitude 4 and 0.5 degrees in diameter. The two are Trumpler class I 3 r clusters, though NGC 869 is a Shapley class f and NGC 884 is a Shapley class e cluster. These classifications indicate that they are both quite rich (dense); NGC 869 is the richer of the pair. The clusters are both distinct from the surrounding star field and are clearly concentrated at their centers. The constituent stars, numbering over 100 in each cluster, range widely in brightness.
Perseus (constellation) | Deep-sky objects
Hydrus is a small constellation in the deep southern sky. It was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman and it first appeared on a 35-cm (14 in) diameter celestial globe published in late 1597 (or early 1598) in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars and gave their Bayer designations in 1756. Its name means "male water snake", as opposed to Hydra, a much larger constellation that represents a female water snake.
Hydrus | Introduction
M35 (NGC 2168) is a large, elongated open cluster of magnitude 5, discovered in the year 1745 by Swiss astronomer Philippe Loys de Chéseaux. It has an area of approximately 0.2 square degrees, the same size as the full moon. Its high magnitude means that M35 is visible to the unaided eye under dark skies; under brighter skies it is discernible in binoculars. The 200 stars of M35 are arranged in chains that curve throughout the cluster; it is 2800 light-years from Earth. Another open cluster in Gemini is NGC 2158. Visible in large amateur telescopes and very rich, it is more than 12,000 light-years from Earth.
Gemini (constellation) | Deep-sky objects
They are within a circle of radius of 1.6 arcmin, corresponding to about 75,000 light-years. Located in the galaxy ESO 243-49 is HLX-1, an intermediate-mass black hole—the first one of its kind identified. It is thought to be a remnant of a dwarf galaxy that was absorbed in a collision with ESO 243-49. Before its discovery, this class of black hole was only hypothesized. Lying within the bounds of the constellation is the gigantic Phoenix cluster, which is around 7.3 million light years wide and 5.7 billion light years away, making it one of the most massive galaxy clusters. It was first discovered in 2010, and the central galaxy is producing an estimated 740 new stars a year.
Phoenix (constellation) | Deep-sky objects
Approximately 200 million light-years from Earth with a redshift of 0.016 is Abell 3627; also called the Norma Cluster, it is one of the most massive galaxy clusters known to exist, at ten times the average cluster mass. Abell 3627 is thus theorized to be the Great Attractor, a massive object that is pulling the Local Group, the Virgo Supercluster, and the Hydra-Centaurus Supercluster towards its location at 600–1000 kilometres per second.
Norma (constellation) | Deep-sky objects
This is dated from 33,000 to 10,000 years ago. He also suggested a panel in the same caves depicting a charging bison, a man with a bird's head and the head of a bird on top of a piece of wood, together may depict the Summer Triangle, which at the time was a circumpolar formation. Rappenglueck also discovered a drawing of the Northern Crown constellation in the cave of El Castillo (North of Spain), made in the same period as the Lascaux chart. Another star chart panel, created more than 21,000 years ago, was found in the (fr). The bovine in this panel may represent the constellation Taurus, with a pattern representing the Pleiades just above it.
Star chart | Prehistory
In the north of the constellation is the Corona Australis Molecular Cloud, a dark molecular cloud with many embedded reflection nebulae, including NGC 6729, NGC 6726–7, and IC 4812. A star-forming region of around , it contains Herbig–Haro objects (protostars) and some very young stars. About 430 light years (130 parsecs) away, it is one of the closest star-forming regions to the Solar System. The related NGC 6726 and 6727, along with unrelated NGC 6729, were first recorded by Johann Friedrich Julius Schmidt in 1865. The Coronet cluster, about 554 light years (170 parsecs) away at the edge of the Gould Belt, is also used in studying star and protoplanetary disk formation.
Corona Australis | Deep sky objects
Camelopardalis is in the part of the celestial sphere facing away from the galactic plane. Accordingly, many distant galaxies are visible within its borders.
Camelopardalis | Deep-sky objects
These are added to pre-existing x-ray data from the Chandra X-ray Observatory and ESAs XMM-Newton, two fields of 10' by 16'; one centered on the Hubble Deep Field North (12h 36m 55s, +62° 14m 15s) and the other on the Chandra Deep Field South (3h 32m 30s, -27° 48m 20s). The two GOODS fields are the most data-rich areas of the sky in terms of depth and wavelength coverage.
Great Observatories Origins Deep Survey | Introduction
Though it probably formed as a disk shape, tidal forces from the Milky Way have distorted it. Along with the Large Magellanic Cloud, it lies within the Magellanic Stream, a cloud of gas that connects the two galaxies. NGC 346 is a star-forming region located in the Small Magellanic Cloud. It has an apparent magnitude of 10.3. Within it lies the triple star system HD 5980, each of its members among the most luminous stars known.
Tucana | Deep-sky objects
The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2.6 arcminutes on a side, about one 24-millionth of the whole sky, which is equivalent in angular size to a tennis ball at a distance of 100 metres. The image was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and 28, 1995. The field is so small that only a few foreground stars in the Milky Way lie within it; thus, almost all of the 3,000 objects in the image are galaxies, some of which are among the youngest and most distant known.
Hubble Deep Field | Introduction
Three interesting planetary nebulae lie in Aquila: More deep-sky objects: Aquila also holds some extragalactic objects. One of them is what may be the largest single mass concentration of galaxies in the Universe known, the Hercules–Corona Borealis Great Wall. It was discovered in November 2013, and has the size of 10 billion light years. It is the biggest and the most massive structure in the Universe known.
Aquila (constellation) | Deep-sky objects
Monoceros contains many clusters and nebulae, most notable among them:
Monoceros | Deep-sky objects
It is also related to IC 4677, a nebula that appears as a bar 1.8 arcminutes to the west of the Cat's Eye nebula. In long-term exposures, IC 4677 appears as a portion of a ring surrounding the planetary nebula. There are several faint galaxies in Draco, one of which is the lenticular galaxy NGC 5866 (sometimes considered to be Messier Object 102) that bears its name to a small group that also includes the spiral galaxies NGC 5879 and NGC 5907. Another is the Draco Dwarf Galaxy, one of the least luminous galaxies with an absolute magnitude of −8.6 and a diameter of only about 3,500 light years, discovered by Albert G.
Draco (constellation) | Deep-sky objects
He arranged his discoveries under eight "classes": (I) bright nebulae, (II) faint nebulae, (III) very faint nebulae, (IV) planetary nebulae, (V) very large nebulae, (VI) very compressed and rich clusters of stars, (VII) compressed clusters of small and large [faint and bright] stars, and (VIII) coarsely scattered clusters of stars. Herschel's discoveries were supplemented by those of Caroline Herschel (11 objects) and his son John Herschel (1754 objects) and published by him as "General Catalogue of Nebulae and Clusters" in 1864. This catalogue was later edited by John Dreyer, supplemented with discoveries by many other 19th-century astronomers, and published in 1888 as the "New General Catalogue" (abbreviated NGC) of 7,840 deep-sky objects.
William Herschel | Deep sky surveys
AT2018cow, a large astronomical explosion detected on 16 June 2018. As of 22 June 2018, this astronomical event has generated a very large amount of interest among astronomers throughout the world and may be, as of 22 June 2018, considered a supernova tentatively named Supernova 2018cow. Hercules contains two bright globular clusters: M13, the brightest globular cluster in the northern hemisphere, and M92. It also contains the nearly spherical planetary nebula Abell 39. M13 lies between the stars η Her and ζ Her; it is dim, but may be detected by the unaided eye on a very clear night. M13, visible to both the naked eye and binoculars, is a globular cluster of the 6th magnitude that contains more than 300,000 stars and is 25,200 light-years from Earth.
Hercules (constellation) | Deep-sky objects
Eventually, the outermost stars may form a dwarf galaxy orbiting M66. Both M65 and M66 are visible in large binoculars or small telescopes, but their concentrated nuclei and elongation are only visible in large amateur instruments. M95 and M96 are both spiral galaxies 20 million light-years from Earth. Though they are visible as fuzzy objects in small telescopes, their structure is only visible in larger instruments. M95 is a barred spiral galaxy. M105 is about a degree away from the M95/M96 pair; it is an elliptical galaxy of the 9th magnitude, also about 20 million light-years from Earth. NGC 2903 is a barred spiral galaxy discovered by William Herschel in 1784.
Leo (constellation) | Deep-sky objects
The Great Rift, a series of dark patches in the Milky Way, is more visible and striking in the southern hemisphere than in the northern. It vividly stands out when conditions are otherwise so dark that the Milky Way's central region casts shadows on the ground. Some cultures have discerned shapes in these patches and have given names to these "dark cloud constellations". Members of the Inca civilization identified various dark areas or dark nebulae in the Milky Way as animals and associated their appearance with the seasonal rains. Australian Aboriginal astronomy also describes dark cloud constellations, the most famous being the "emu in the sky" whose head is formed by the Coalsack, a dark nebula, instead of the stars.
Constellation | Dark cloud constellations
NGC 3395 and NGC 3396 are a spiral and irregular barred spiral galaxy, respectively, that are interacting, located 1.33 degrees southwest of 46 Leonis Minoris. The unique deep-sky object known as Hanny's Voorwerp was discovered in Leo Minor in 2007 by Dutch school teacher Hanny van Arkel while participating as a volunteer in the Galaxy Zoo project. Lying near the 650-million-light-year-distant spiral galaxy IC 2497, it is around the same size as the Milky Way. It contains a 16,000-light-year-wide hole. The voorwerp is thought to be the visual light echo of a quasar now gone inactive, possibly as recently as 200,000 years ago.
Leo Minor | Deep-sky objects
The Hubble Ultra-Deep Field (HUDF) is an image of a small region of space in the constellation Fornax, containing an estimated 10,000 galaxies. The original release was combined from Hubble Space Telescope data accumulated over a period from September 24, 2003, through to January 16, 2004. Looking back approximately 13 billion years (between 400 and 800 million years after the Big Bang) it has been used to search for galaxies that existed at that time. The HUDF image was taken in a section of the sky with a low density of bright stars in the near-field, allowing much better viewing of dimmer, more distant objects.
Hubble Ultra-Deep Field | Introduction
The cluster was recorded in 1751-2 by Nicolas-Louis de Lacaille, who initially thought it was the nucleus of a bright comet. Lacaille then listed it as "Lac I-1", the first object listed in his deep-sky catalogue. The number "47" was assigned in "Allgemeine Beschreibung und Nachweisung der Gestirne nebst Verzeichniss" ("General description and verification of the stars and indexes"), compiled by Johann Elert Bode and published in Berlin in 1801. Bode did not observe this cluster himself, but had reordered Lacaille's catalogued stars by constellation in order of Right Ascension. In the 19th century, Benjamin Apthorp Gould assigned the Greek letter ξ (Xi) to the cluster to designate it ξ Tucanae, but this was not widely adopted and it is almost universally referred to as 47 Tucanae.
47 Tucanae | Early history
Towards the north of the constellation are globular clusters NGC 5824 and NGC 5986, and close by the dark nebula B 228. To the south are two open clusters, NGC 5822 and NGC 5749, as well as globular cluster NGC 5927 on the eastern border with Norma. On the western border are two spiral galaxies and the Wolf–Rayet planetary nebula IC 4406, containing some of the hottest stars in existence. IC 4406, also called the Retina Nebula, is a cylindrical nebula at a distance of 5,000 light-years. It has dust lanes throughout its center. Another planetary nebula, NGC 5882, is towards the center of the constellation.
Lupus (constellation) | Deep-sky objects
It is located 5 degrees south of Epsilon Trianguli Australis. ESO 69-6 is a pair of merging galaxies located about 600 million light-years (185 megaparsecs) away. Their contents have been dragged out in long tails by the interaction.
Triangulum Australe | Deep-sky objects
The word "constellation" comes from the Late Latin term , which can be translated as "set of stars"; it came into use in English during the 14th century. The Ancient Greek word for constellation is ἄστρον. These terms generally referred to a recognisable pattern of stars whose appearance is associated with mythological characters or creatures, earthbound animals, or objects. A more modern astronomical sense of the term "constellation" denotes one of the 88 IAU designated constellations recognized today. Colloquial usage does not draw a sharp distinction between "constellations" and smaller "asterisms" (pattern of stars), yet the modern accepted astronomical constellations employ such a distinction.
Constellation | Terminology
There are many astronomical object types that come under the description of "deep-sky objects". Since the definition is objects that are non-Solar System and non-stellar the list includes:
Deep-sky object | List of deep-sky object types
Atlas labors under the weight because he had been sentenced by Zeus to hold up the sky. The sphere shows a depiction of the night sky as seen from outside the outermost celestial sphere, with low reliefs depicting 41 (some sources say 42) of the 48 classical Greek constellations distinguished by Ptolemy, including Aries the ram, Cygnus the swan and Hercules the hero. The sculpture stands tall, and the sphere is in diameter.
Farnese Atlas | Introduction
Of the deep-sky objects of interest in Vela is a planetary nebula known as the NGC 3132, nicknamed the 'Eight-Burst Nebula' or 'Southern Ring Nebula' (see accompanying photo). It lies on the border of the constellation with Antlia. NGC 2899 is an unusual red-hued example. This constellation has 32 more planetary nebulae. The Gum Nebula is a faint emission nebula, believed to be the remains of a million-year-old supernova. Within it lie the smaller and younger Vela Supernova Remnant. This is the nebula of a supernova explosion that is believed to have been visible from Earth around 10,000 years ago.
Vela (constellation) | Deep-sky objects
Due to its location on the Milky Way, this constellation contains many deep-sky objects such as star clusters, including eight open clusters visible through binoculars. NGC 6087 is the brightest of the open clusters in Norma with a magnitude of 5.4. It lies in the southeastern corner of the constellation between Alpha Centauri and Zeta Arae. Thought to be around 100 million years old, it is about 3300 light-years away and is around 14 light-years in diameter. Its brightest member is the Cepheid variable S Normae. A rich background star field makes it less distinct, though around 36 member stars are visible though a 10 cm telescope at 150x magnification.
Norma (constellation) | Deep-sky objects
Appearing ring-shaped, it is thought that it actually is cylindrical and oriented directly at Earth. Around 8700 years old, it lies about five degrees west-northwest of Gamma Normae. Its integrated magnitude is 13.6 and its mean surface brightness is 13.9. The central star is a white dwarf of magnitude 14.03. Mz 1 is a bipolar planetary nebula, thought to be an hourglass shape tilted at an angle to observers on Earth, some 3500 light-years distant. Mz 3—known as the Ant Nebula as it resembles an ant—has a complex appearance, with at least four outflow jets and two large lobes visible.
Norma (constellation) | Deep-sky objects
The Celestial Diagram consisted of a northern and a southern panel which depicted circumpolar constellations in the form of discs; each divided into 24 sections suggesting a 24-hour time period, lunar cycles, and sacred deities of Egypt. Of the constellations present on the diagram, the only certainly identifiable was Meskhetyu with the Big Dipper because of the difficulty that arises when an attempt is made to match modern day constellations with the depictions made thousands of years ago by the ancient Egyptians. The map on the southern panel could well reflect a specific conjunction of planets in 1534 BCE around the longitude of Sirius.
Astronomical ceiling of Senenmut's Tomb | Celestial Diagram
There is one Messier object in Lepus, M79. It is a globular cluster of magnitude 8.0, 42,000 light-years from Earth. One of the few globular clusters visible in the Northern Celestial Hemisphere's winter, it is a Shapley class V cluster, which means that it has an intermediate concentration towards its center. It is often described as having a "starfish" shape. M79 was discovered in 1780 by Pierre Méchain.
Lepus (constellation) | Deep-sky objects
NGC 7172, NGC 7174 and NGC 7314 are three galaxies of magnitudes 11.9, 12.5 and 10.9, respectively. NGC 7259 is another spiral galaxy, which hosted a supernova—SN 2009ip—in 2009. At redshift z = 0.116, the BL Lacertae object PKS 2155-304 is one of the brightest blazars in the sky.
Piscis Austrinus | Deep sky objects
This globe was produced in collaboration with the Amsterdam cartographer Jodocus Hondius. Plancius's constellations (mostly referring to animals and subjects described in natural history books and travellers' journals of his day) are Apis the Bee (later changed to Musca by Lacaille), Apus the Bird of Paradise, Chamaeleon, Dorado the Goldfish (or Swordfish), Grus the Crane, Hydrus the Small Water Snake, Indus the Indian, Pavo the Peacock, Phoenix, Triangulum Australe the Southern Triangle, Tucana the Toucan, and Volans the Flying Fish. The acceptance of these new constellations was assured when Johann Bayer, a German astronomer, included them in his "Uranometria" of 1603, the leading star atlas of its day.
List of Dutch explorations | First systematic mapping of southern celestial hemisphere (1595–1597)
Camelopardalis is a large but faint constellation of the northern sky representing a giraffe. The constellation was introduced in 1612 or 1613 by Petrus Plancius. Some older astronomy books give Camelopardalus or Camelopardus as alternative forms of the name, but the version recognized by the International Astronomical Union matches the genitive form, seen suffixed to most of its key stars.
Camelopardalis | Introduction
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" (which in turn has roots that go back to Mesopotamian astronomy), 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.
Constellation family | Introduction
Historically, the origins of the constellations of the northern and southern skies are distinctly different. Most northern constellations date to antiquity, with names based mostly on Classical Greek legends. Evidence of these constellations has survived in the form of star charts, whose oldest representation appears on the statue known as the Farnese Atlas, based perhaps on the star catalogue of the Greek astronomer Hipparchus. Southern constellations are more modern inventions, sometimes as substitutes for ancient constellations (e.g. Argo Navis). Some southern constellations had long names that were shortened to more usable forms; e.g. Musca Australis became simply Musca. Some of the early constellations were never universally adopted.
Constellation | Early modern astronomy
Due to its small size and location away from the plane of the Milky Way, Caelum is rather devoid of deep-sky objects, and contains no Messier objects. The only deep-sky object in Caelum to receive much attention is HE0450-2958, an unusual Seyfert galaxy. Originally, the jet's host galaxy proved elusive to find, and this jet appeared to be emanating from nothing. Although it has been suggested that the object is an ejected supermassive black hole, the host is now agreed to be a small galaxy that is difficult to see due to light from the jet and a nearby starburst galaxy.
Caelum | Deep-sky objects
First Man, First Woman, Great Coyote, and the Holy People next planned stars for the night sky. They gathered as many pieces of , "rock-star mica," as they could find, and put them on a blanket. Then First Man made a drawing in the dirt to plan the location of all the stars seeking to make the sky like a woven rug, orderly and balanced. , Black Yéʼii, placed the (North Star). First Man placed the (Big Dipper) while First Woman put the (Little Dipper) into the sky. First Man also placed the (Seven Stars, the Pleiades) which Black Yéʼii claimed represented parts of his body.
Diné Bahaneʼ | Stars and Constellations
In astronomy, a deep field is an image of a portion of the sky taken with a very long exposure time, in order to detect and study faint objects. The depth of the field refers to the apparent magnitude or the flux of the faintest objects that can be detected in the image. Deep field observations usually cover a small angular area on the sky, because of the large amounts of telescope time required to reach faint flux limits. Deep fields are used primarily to study galaxy evolution and the cosmic evolution of active galactic nuclei, and to detect faint objects at high redshift.
List of deep fields | Introduction