A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his Catalogue des Nébuleuses et des Amas d'Étoiles. Because Messier was interested only in finding comets, he created a list of those non-comet objects that frustrated his hunt for them. This list, which Messier created in collaboration with his assistant Pierre Méchain, is now known as the Messier catalogue. The Messier catalogue is one of the most famous lists of astronomical objects, and many objects on the list are still referenced by their Messier numbers. The catalogue includes most of the astronomical deep-sky objects that can be easily observed from Earth's Northern Hemisphere; many Messier objects are popular targets for amateur astronomers.
Wil Tirion is a Dutch uranographer. His most famous work, Sky Atlas 2000.0, is renowned by astronomers for its accuracy and beauty. The second edition of his most complete work, Uranometria 2000.0, was published in 2001 by Willmann-Bell. He is also responsible for the sky charts found in many other publications. He was originally a graphic designer. The minor planet (asteroid) 4648 Tirion is named after him.
Messier 41 (also known as M41 or NGC 2287) is an open cluster in the constellation Canis Major. It is 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 Lagoon Nebula is a giant interstellar cloud in the constellation Sagittarius. It is classified as an emission nebula and has an H II region.
Messier 35 or M35, also known as NGC 2168 or the Shoe-Buckle Cluster, is a relatively close open cluster of stars in the west of Gemini, at about the declination of the sun when the latter is at June solstice. It was discovered by Philippe Loys de Chéseaux around 1745 and independently discovered by John Bevis before 1750. It is scattered over part of the sky almost the size of the full moon and is 2,970 light-years away. The compact open cluster NGC 2158 lies directly southwest of it.
Messier 39 or M39, also known as NGC 7092, is an open cluster of stars in the constellation of Cygnus, positioned two degrees to the south of the star Pi Cygni and around 9° east-northeast of Deneb. The cluster was discovered by Guillaume Le Gentil in 1749, then Charles Messier added it to his catalogue in 1764. When observed in a small telescope at low power the cluster shows around two dozen members but is best observed with binoculars. It has a total integrated magnitude (brightness) of 5.5 and spans an angular diameter of 29 arcminutes – about the size of the full Moon. It is centered about 1,010 light-years away.
Messier 47 is an open cluster in the mildly southern constellation of Puppis. It was discovered by Giovanni Batista Hodierna before 1654 and in his then keynote work re-discovered by Charles Messier on 1771. It was also independently discovered by Caroline Herschel.
Messier 68 is a globular cluster found in the east south-east of Hydra, away from its precisely equatorial part. It was discovered by Charles Messier in 1780. William Herschel described it as "a beautiful cluster of stars, extremely rich, and so compressed that most of the stars are blended together". His son John noted that it was "all clearly resolved into stars of 12th magnitude, very loose and ragged at the borders".
NGC 7789 is an open cluster in Cassiopeia that was discovered by Caroline Herschel in 1783. Her brother William Herschel included it in his catalog as H VI.30. This cluster is also known as the "White Rose" Cluster or "Caroline's Rose" Cluster because when seen visually, the loops of stars and dark lanes look like the swirling pattern of rose petals as seen from above.
NGC 1514, also known as the Crystal Ball Nebula, is a planetary nebula in the zodiac constellation of Taurus, positioned to the north of the star Psi Tauri along the constellation border with Perseus. Distance to the nebula is 466 pc, according to GAIA DR2 data.
NGC 6210, sometimes also known as the Turtle Nebula, is a planetary nebula located in the constellation Hercules, approximately 5.4 ± 1.3 kly from the Sun. It is positioned about 38° above the galactic plane at a vertical distance of about 3.3 kilolight-years (1 kpc) and thus has little extinction from intervening interstellar dust. This object was first recorded as a star-like feature by Joseph Lalande on March 22, 1799. However, credit for the discovery of a nebula goes to Wilhelm Struve in 1825. John L. E. Dreyer described it as, "a planetary nebula, very bright, very small, round, disc and border".
Celestial cartography, uranography, astrography or star cartography is the aspect of astronomy and branch of cartography concerned with mapping stars, galaxies, and other astronomical objects on the celestial sphere. Measuring the position and light of charted objects requires a variety of instruments and techniques. These techniques have developed from angle measurements with quadrants and the unaided eye, through sextants combined with lenses for light magnification, up to current methods which include computer-automated space telescopes. Uranographers have historically produced planetary position tables, star tables, and star maps for use by both amateur and professional astronomers. More recently, computerized star maps have been compiled, and automated positioning of telescopes uses databases of stars and of other astronomical objects.
NGC 1555, sometimes known as Hind's Variable Nebula, Sh2-238 or HH 155, is a variable nebula 4 light years across, illuminated by the star T Tauri, located in the constellation Taurus. It is 400 light years away from Earth, and has a magnitude (B) of 9.98. It is also in the second Sharpless catalog as 238. It is a Herbig–Haro object. The nebula was discovered on October 11, 1852, by John Russell Hind.
NGC 3632 and NGC 3626 is an unbarred lenticular galaxy and Caldwell object in the constellation Leo. It was discovered by William Herschel, on 14 March 1784. It shines at magnitude +10.6/+10.9. Its celestial coordinates are RA 11h 20.1m, dec +18° 21′. It is located near the naked-eye-class A4 star Zosma, as well as galaxies NGC 3608, NGC 3607, NGC 3659, NGC 3686, NGC 3684, NGC 3691, NGC 3681, and NGC 3655. Its dimensions are 2′.7 × 1′.9. The galaxy belongs to the NGC 3607 group some 70 million light-years distant, itself one of the many Leo II groups.
Abell 262 is a galaxy cluster in the Abell catalogue. It is part of the Perseus–Pisces Supercluster, one of the largest known structures in the universe. Although its central galaxy, NGC 708, is a giant cD galaxy, most of its bright galaxies are spirals, which is unusual for a galaxy cluster. With approximately 200 members it is a comparatively small cluster.
NGC 1288 is an intermediate barred spiral galaxy located about 196 million light years away in the constellation Fornax. In the nineteenth century, English astronomer John Herschel described it as "very faint, large, round, very gradually little brighter middle." The morphological classification of SABc(rs) indicates weak bar structure across the nucleus (SAB), an incomplete inner ring orbiting outside the bar (rs), and the multiple spiral arms are moderately wound (c). The spiral arms branch at intervals of 120° at a radius of 30″ from the nucleus. The galaxy is most likely surrounded by a dark matter halo, giving it a mass-to-light ratio of 14 M☉/L☉.
NGC 1342, sometimes also known as the Stingray Cluster, is an open cluster in the constellation Perseus. It was discovered by William Herschel on 28 December 1799. It is located in the south of the constellation, almost halfway between Algol and ζ Persei, away from the plane of the Milky Way. NGC 1342 has an apparent size of 17' and an apparent magnitude of 6.7, marginally visible by naked eye. In 1994, Peña, J. H. and Peniche, R. estimated by the use of photometric data, that the age of the cluster is 400 million years.
NGC 6441, sometimes also known as the Silver Nugget Cluster, is a globular cluster in the southern constellation of Scorpius. It was discovered by the Scottish astronomer James Dunlop on May 13, 1826, who described it as "a small, well-defined rather bright nebula, about 20″ in diameter". The cluster is located 5 arc minutes east-northeast of the star G Scorpii, and is some 43,000 light-years from the Sun.
UGC 8837 is a dwarf galaxy located in the constellation of Ursa Major, 24 million light years away from Earth. It is a member of the M101 Group, a group containing several galaxies orbiting the largest, the Pinwheel Galaxy (M101).
