Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross. Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.
Corona Australis is a constellation in the Southern Celestial Hemisphere. Its Latin name means "southern crown", and it is the southern counterpart of Corona Borealis, the northern crown. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. The Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, a tent, or even a hut belonging to a rock hyrax.
Sagittarius is one of the constellations of the zodiac and is located in the Southern celestial hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy and remains one of the 88 modern constellations. Its old astronomical symbol is (♐︎). Its name is Latin for "archer". Sagittarius is commonly represented as a centaur pulling back a bow. It lies between Scorpius and Ophiuchus to the west and Capricornus and Microscopium to the east.
Vela is a constellation in the southern sky, which contains the Vela Supercluster. Its name is Latin for the sails of a ship, and it was originally part of a larger constellation, the ship Argo Navis, which was later divided into three parts, the others being Carina and Puppis. With an apparent magnitude of 1.8, its brightest star is the hot blue multiple star Gamma Velorum, one component of which is the brightest Wolf-Rayet star in the sky. Delta and Kappa Velorum, together with Epsilon and Iota Carinae, form the asterism known as the False Cross. 1.95-magnitude Delta is actually a triple or quintuple star system.
The Ring Nebula is a planetary nebula in the mildly northern constellation of Lyra. Such a nebula is formed when a star, during the last stages of its evolution before becoming a white dwarf, expels a vast luminous envelope of ionized gas into the surrounding interstellar space.
Perseus is a constellation in the northern sky, being 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.
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees, and also the longest at over 100 degrees. Its southern end borders Libra and Centaurus and its northern end borders Cancer. It was included among the 48 constellations listed by the 2nd century astronomer Ptolemy. Commonly represented as a water snake, it straddles the celestial equator.
Messier 41 (also known as M41 or NGC 2287) is an open cluster in the constellation Canis Major, sometimes referred to as The Little Beehive Cluster. It was discovered by Giovanni Batista Hodierna before 1654 and was perhaps known to Aristotle about 325 BC. It lies about four degrees almost exactly south of Sirius, with which it forms a roughly equilateral triangle with Nu2 Canis Majoris to the west—all three figure in the same field in binoculars.
The Small Sagittarius Star Cloud is a star cloud in the constellation of Sagittarius approximately 600 light years wide, which was catalogued by Charles Messier in 1764. It should not be confused with the nearby Large Sagittarius Star Cloud which lies about 10° to the south.
NGC 6633 is a large bright open cluster in the constellation Ophiuchus. Discovered in 1745-46 by Philippe Loys de Chéseaux, it was independently rediscovered by Caroline Herschel in 1783 and included in her brother William's catalog as H VIII.72. Bright enough to be seen with the naked eye, the cluster is considered a fine object for binoculars or small telescopes.
NGC 288 is a globular cluster in the constellation Sculptor. Its visual appearance was described by John Dreyer in 1888. It is located about 1.8° southeast of the galaxy NGC 253, 37′ north-northeast of the South Galactic Pole, 15′ south-southeast of a 9th magnitude star, and encompassed by a half-circular chain of stars that opens on its southwest side. It can be observed through binoculars. It is not very concentrated and has a well resolved, large 3′ dense core that is surrounded by a much more diffuse and irregular 9′ diameter ring. Peripheral members extend farther outward towards the south and especially southwest.
NGC 6834 is a young open cluster of stars located about 10,850 light years from the Sun in the constellation Cygnus. It was discovered on July 17, 1784 by Anglo-German astronomer William Herschel. The cluster has a visual magnitude of 7.8, which is dimmed by 2.1 magnitudes due to interstellar dust. Half the cluster members lie within an angular radius of 6′.
NGC 6067 is an open cluster in the constellation Norma. It is located to the north of Kappa Normae, with an angular diameter of 12′. Visible to the naked eye in dark skies, it is best observed with binoculars or a small telescope, and a 12-inch aperture telescope will reveal about 250 stars. Discovered by James Dunlop in 1826, it has been described by John Herschel as "a most superbly rich and large cluster" and by Stephen James O'Meara as "one of the sky’s most stunning open star clusters". Its brightest stars have an apparent magnitude of around 8. There are 84 member stars with an apparent magnitude brighter than 12.
NGC 6624 is a globular cluster in the constellation Sagittarius. It was discovered on 24 June 1784 by the astronomer William Herschel. It is given an apparent magnitude of 7.6 to 8.5. Six pulsars are known in NGC 6624. The first of these to be discovered was PSR J1823-3021A. This globular cluster also contains 4U 1820-30, a low-mass X-ray binary with an orbital period of only 11.5 minutes.
NGC 6811 is an open cluster in the constellation of Cygnus, near the constellation of Lyra. It has an angular size half that of the full Moon and includes about 1000 stars of roughly similar magnitude. It has also been called "The Hole in the Cluster" because of its dark center.
NGC 1528 is an open cluster in the constellation Perseus. It was discovered by William Herschel in 1790. It is located in the north-eastern part of the constellation, just under 3 degrees north of μ Persei. Less than 1.5° to the southeast is the open cluster NGC 1545. The NGC 1528 is clearly visible with 10x50 binoculars. 165 stars are recognised as members of NGC 1528, the brightest of which has apparent magnitude 8.7.
NGC 1545 is an open cluster in the constellation Perseus. It was discovered by William Herschel on December 28, 1790. It is located in the north-eastern part of the constellation, a few arcminutes east of the 4.5 magnitude star b Persei, near the equally large and bright NGC 1528, which is less than 1.5° towards the northwest. However, it is less dense and rich. The brightest star of the cluster is a K5 III giant star, with 7.1 magnitude, but its membership is questionable. One more 7.9 magnitude star is visible at the north edge of the cluster.
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 1624, also known as Sh2-212 in the Sharpless catalog, is a very young open cluster located in the constellation Perseus inside an emission nebula. It was discovered by the German-British astronomer William Herschel in 1790. NGC 1624 is located at about 20,000 ly away and the latest estimates give an age of less than 4 million years. The apparent magnitude is 11.8, and apparent diameter is about 3.0 arc minutes. Its celestial location is right ascension (α) 04h 40m 36.0s and declination (δ) +50° 27′ 42″. It is potentially an area of massive star formation.
NGC 6910 is an open cluster in the constellation Cygnus. It was discovered by William Herschel on October 17, 1786. The cluster was also observed by John Herschel on September 18, 1828. It is a poor cluster and with prominent central concentration, with Trumpler class I2p. NGC 6910 is the core cluster of the stellar association Cygnus OB9.
