Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and one of the 88 modern constellations. Located in the northern celestial hemisphere, it is named for Andromeda, daughter of Cassiopeia, in the Greek myth, who was chained to a rock to be eaten by the sea monster Cetus. Andromeda is most prominent during autumn evenings in the Northern Hemisphere, along with several other constellations named for characters in the Perseus myth. Because of its northern declination, Andromeda is visible only north of 40° south latitude; for observers farther south, it lies below the horizon. It is one of the largest constellations, with an area of 722 square degrees. This is over 1,400 times the size of the full moon, 55% of the size of the largest constellation, Hydra, and over 10 times the size of the smallest constellation, Crux.
Perseus is a constellation in the northern sky, named after the Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north. Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose asterism was named together as Perseus et Caput Medusae; however, this never came into popular usage.
Cepheus is a constellation in the far northern sky, named after Cepheus, a king of Aethiopia in Greek mythology. It is one of the 48 constellations listed by the second century astronomer Ptolemy, and it remains one of the 88 constellations in the modern times.
NGC 6397 is a globular cluster in the constellation Ara. It is located about 7,800 light-years from Earth, making it one of the two nearest globular clusters to Earth. The cluster contains around 400,000 stars, and can be seen with the naked eye under good observing conditions.
Messier 18 or M18, also designated NGC 6613, is an open cluster of stars in the constellation Sagittarius. It was discovered by Charles Messier in 1764 and included in his list of comet-like objects. From the perspective of Earth, M18 is situated between the Omega Nebula (M17) and the Small Sagittarius Star Cloud (M24).
NGC 6946, sometimes referred to as the Fireworks Galaxy, is a face-on intermediate spiral galaxy with a small bright nucleus, whose location in the sky straddles the boundary between the northern constellations of Cepheus and Cygnus. Its distance from Earth is about 25.2 million light-years or 7.72 megaparsecs, similar to the distance of M101 in the constellation Ursa Major. Both were once considered to be part of the Local Group, but are now known to be among the dozen bright spiral galaxies near the Milky Way but beyond the confines of the Local Group. NGC 6946 lies within the Virgo Supercluster.
NGC 2419 is a globular cluster in the constellation Lynx. It was discovered by William Herschel on December 31, 1788. NGC 2419 is at a distance of about 300,000 light years from the Solar System and at the same distance from the Galactic Center.
NGC 7510 is an open cluster of stars located around 11,400 light years away in the constellation Cepheus, near the border with Cassiopeia. At this distance, the light from the cluster has undergone extinction from interstellar gas and dust equal to E(B – V) = 0.90 ± 0.02 magnitude in the UBV photometric system. Its brightest member is a giant star with a stellar classification of B1.5 III. This cluster forms part of the Perseus Spiral Arm. It has a Trumpler class rating of II 2 m and is around 10 million years old.
NGC 7380 is a young open cluster of stars in the northern circumpolar constellation of Cepheus, discovered by Caroline Herschel in 1787. The surrounding emission nebulosity is known colloquially as the Wizard Nebula, which spans an angle of 25′. German-born astronomer William Herschel included his sister's discovery in his catalog, and labelled it H VIII.77. The nebula is known as S 142 in the 1959 Sharpless catalog (Sh2-142). It is extremely difficult to observe visually, usually requiring very dark skies and an O-III filter. The NGC 7380 complex is located at a distance of approximately 8.5 kilolight-years from the Sun, in the Perseus Arm of the Milky Way.
NGC 7142 is an open cluster about 6,200 light-years away in the constellation Cepheus.
NGC 6709 is an open cluster of stars in the equatorial constellation of Aquila, some 5° to the southwest of the star Zeta Aquilae. It is situated toward the center of the galaxy at a distance of 3,510 light-years.
NGC 2281 is an open cluster of stars in the northern constellation of Auriga. It was discovered by English astronomer William Herschel on March 4, 1788 and described as a, "cluster of coarsely scattered pretty [bright] stars, pretty rich". The Trumpler class for NGC 2281 is I3p, indicating a poor (p) but compact (I) grouping with a wide range of brightness (3). It is located at a distance of approximately 1,720 ly from the Sun and is 630–661 million years old.
NGC 5694 is a globular cluster in the constellation Hydra. It was discovered in 1784 by William Herschel.
NGC 2439 is a sparse open cluster of stars in the constellation Puppis. It has an apparent visual magnitude of 6.9, an angular size of 10 arcminutes, and is visible using a small telescope. This is a young cluster with age estimates in the range of 20–300 million years. It has a tidal radius of approximately 82 light years. No chemically peculiar stars have been found.
NGC 654 is an open cluster in the constellation Cassiopeia. It was discovered by William Herschel in 1787. With apparent magnitude 6.5, it can be observed by binoculars. It is located 2,5° northeast of the star Delta Cassiopeiae. In the same low power field can also be seen the open clusters NGC 663 and NGC 659. It surrounds a 7th magnitude yellowish star, an F5Ia supergiant, which is a possible member of the group.
Cepheus OB1 is an OB association around the cluster NGC 7380. The region is approximately 3,400 parsecs from Earth in the constellation of Cepheus.
NGC 6939 is an open cluster in the constellation Cepheus. It was discovered by William Herschel in 1798. The cluster lies 2/3° northwest from the spiral galaxy NGC 6946. The cluster lies approximately 4,000 light years away and it is over a billion years old.
NGC 1380 is a lenticular galaxy located in the constellation Fornax. It is located at a distance of circa 60 million light years from Earth, which, given its apparent dimensions, means that NGC 1380 is about 85,000 light years across. It was discovered by James Dunlop on September 2, 1826. It is a member of the Fornax Cluster.
NGC 7160 is an open cluster in the constellation Cepheus. It was discovered by William Herschel on November 9, 1789. The cluster was also observed by John Herschel on October 7, 1829. It is a poor cluster and with little central concentration, with Trumpler class II3p. It is part of the stellar association Cepheus OB2, located one degree south-southwest of VV Cephei.
