Crater constellation is located in the southern sky. Its name means “the cup” in Latin.
Crater is one of the Greek constellations. In mythology, it represents the cup of the Greek god Apollo. The constellation was first catalogued by the Greek astronomer Ptolemy in the 2nd century.
Crater is relatively faint, with no stars brighter than fourth magnitude. There are also few notable deep sky objects in the constellation. Most galaxies found in Crater are magnitude 12 or fainter. One of these, the Crater 2 dwarf galaxy, is the fourth largest dwarf galaxy orbiting the Milky Way, but it went undetected until April 2016 because it is also one of the lowest surface brightness dwarfs.
FACTS, LOCATION & MAP
Crater is the 53rd constellation in size, occupying an area of 282 square degrees. It is located in the second quadrant of the southern hemisphere (SQ2) and can be seen at latitudes between +65° and -90°. The neighboring constellations are Corvus, Hydra, Leo, Sextans, and Virgo.
Crater belongs to the Hercules family of constellations, along with Aquila, Ara, Centaurus, Corona Australis, Corvus, Crux, Cygnus, Hercules, Hydra, Lupus, Lyra, Ophiuchus, Sagitta, Scutum, Sextans, Serpens, Triangulum Australe, and Vulpecula.
Crater has three stars with known planets and contains no Messier objects. The brightest star in the constellation is Delta Crateris, with an apparent magnitude of 3.56. There is one meteor shower associated with the constellation; the Eta Craterids.
In Greek mythology, the Crater constellation represents the cup of the god Apollo. The cup is usually depicted as a two-handed chalice. The constellation is associated with the story of Apollo and his sacred bird, either the crow or the raven, which is represented by the neighbouring constellation Corvus.
In the story, the god Apollo is about to make a sacrifice on the altar and he needs some water to perform the ritual. The god sends the raven to promptly fetch some water in his cup, but the bird gets distracted by a fig tree and spends a few days lazily resting and waiting for the figs to ripen. After feasting on the figs, the raven finally brings Apollo the cup filled with water and he also brings a water snake (Hydra) as an excuse for being so late. Apollo sees through the raven’s lies and angrily casts all three – the cup (Crater), the water snake (Hydra) and the raven (Corvus) into the sky.
Apollo also casts a curse on the raven, scorching its feathers and making the bird eternally thirsty and unable to do anything about it. This, according to the myth, is how crows and ravens came to have black feathers and why they have such raspy voices.
MAJOR STARS IN CRATER
Labrum – δ Crateris (Delta Crateris)
Delta Crateris is an orange giant, approximately 196 light years distant. The star belongs to the spectral class K0III and has an apparent visual magnitude of 3.56. It is the brightest star in the constellation.
Delta Crateris is sometimes known as Labrum, which means “the lip” in Latin. The name is associated with the story of the Holy Grail.
Alkes – α Crateris (Alpha Crateris)
Alpha Crateris is a class K1 orange giant, approximately 174 light years from Earth.
It has a visual magnitude of 4.07. It is located relatively close to the Galactic centre and is rich with heavy elements.
Alkes is 80 times more luminous than the Sun. Its traditional name is derived from the Arabic alkās, which means “the cup.”
Al Sharasif – β Crateris (Beta Crateris)
Beta Crateris is a white sub-giant belonging to the spectral class A2III. The star has an apparent magnitude of 4.48 and is approximately 266 light years distant from the solar system.
Beta Crateris is sometimes known by its traditional name, Al Sharasif, which means “the ribs” in Arabic. The star shares the name with Nu Hydrae.
γ Crateris (Gamma Crateris)
Gamma Crateris is the second brightest star in Corvus. It is a close binary star approximately 84 light years distant. The brighter component in the system is a white dwarf, a class A9V star with an apparent magnitude of 4.06. The companion star has a visual magnitude of 9.6.
SZ Crateris is a variable star only 42.9 light years distant from Earth. It has a visual magnitude that varies from 8.61 to 11.0. It is really a binary star system composed of two main sequence stars, belonging to the spectral types K5V and M0V.
SZ Crateris is a BY Draconis type variable, a star exhibiting variations in luminosity as a result of its rotation, star spots and other activity in its chromosphere. The star’s optical period is 11.58 days. It is believed to be less than 200 million years old.
The system belongs to the Ursa Major moving group (Collinder 285), a group of stars that share a similar motion through space, which includes most of the brightest stars in the constellation Ursa Major.
R Crateris is an SRb-type semi-regular variable star belonging to the spectral class M7. The star has an apparent magnitude that varies between 9.8 and 11.2 and an optical period of 160 days.
DEEP SKY OBJECTS IN CRATER
NGC 3887 is an 11th magnitude barred spiral galaxy in Crater. It has a diameter of 3.5’.
The galaxy lies about a degree and half from the star Zeta Crateris. It has an apparent visual magnitude of 10.7 and is about 68 million light years distant.
It was discovered in 1785 by Sir William Herschel.
NGC 3511 is a spiral galaxy in Crater, seen almost edge-on.
The galaxy has an apparent magnitude of 11.1. It belongs to the Abell 1060 galaxy cluster.
NGC 3511 has a slight bar and is classified as a SBbc type galaxy. It was discovered by William Herschel on December 21, 1786.
NGC 3513 is also a spiral galaxy, found in the same field of view as NGC 3511. It has an apparent magnitude of 12 and lies approximately 46 million light years from Earth.
NGC 3981 is a magnitude 12 SBbc type spiral galaxy. It has two very wide spiral arms and is 3’ in diameter.
Like NGC 3887, NGC 3981 was discovered by Sir William Herschel in 1785. It is approximately 80 million light years distant from Earth.
Crater 2 is one of the dwarf galaxies orbiting the Milky Way. It is the fourth largest dwarf orbiting our galaxy, smaller only than the Large Magellanic Cloud, Small Magellanic Cloud and the Sagittarius Dwarf.
The galaxy lies at a distance of only about 380,000 light years from the Sun. In spite of its size and proximity, Crater 2 was only discovered in 2016 because its stars are spread out from one another, which led researchers to nickname the galaxy “the feeble giant.”