NGC 6540 | |
---|---|
Observation data (J2000 epoch) | |
Constellation | Sagittarius |
Right ascension | 18h 06m 08.60s [1] |
Declination | −27° 45′ 55.0″ [1] |
Distance | 17.3 kly (5.3 kpc) |
Apparent magnitude (V) | 9.30 [2] |
Physical characteristics | |
Absolute magnitude | -6.35 [2] |
Radius | 4.75' x 4.75' [2] |
Metallicity | = -1.35 [3] dex |
Other designations | Cr 364, Djorg 3, VDBH 258, C 1803-278 [1] |
NGC 6540 is a globular cluster in the constellation Sagittarius. Its apparent magnitude is 9.3 [2] and its diameter is about 9.5 arcminutes, with 12 faint stars visible. It is about 17,000 light years away from Earth and was discovered by Wilhelm Herschel on May 24, 1784, with an 18.7-inch mirror telescope, who described the cluster as "pretty faint, not large, crookedly extended, easily resolvable".
Coma Berenices is an ancient asterism in the northern sky, which has been defined as one of the 88 modern constellations. It is in the direction of the fourth galactic quadrant, between Leo and Boötes, and it is visible in both hemispheres. Its name means "Berenice's Hair" in Latin and refers to Queen Berenice II of Egypt, who sacrificed her long hair as a votive offering. It was introduced to Western astronomy during the third century BC by Conon of Samos and was further corroborated as a constellation by Gerardus Mercator and Tycho Brahe. It is the only modern constellation named for a historic person.
Messier 14 is a globular cluster of stars in the constellation Ophiuchus. It was discovered by Charles Messier in 1764.
Messier 72 is a globular cluster in the south west of the very mildly southern constellation of Aquarius.
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.
The Butterfly Cluster is an open cluster of stars in the southern constellation of Scorpius. Its name derives from the vague resemblance of its shape to a butterfly. The Trumpler classification of II 3 r encodes it is rich in stars, ranks II out of IV for disparateness and greatly mixes bright with faint components. It is 3.5° to the northwest of Messier 7, both north of the tail of Scorpius.
Messier 12 or M 12 is a globular cluster in the constellation of Ophiuchus. It was discovered by the French astronomer Charles Messier on May 30, 1764, who described it as a "nebula without stars". In dark conditions this cluster can be faintly seen with a pair of binoculars. Resolving the stellar components requires a telescope with an aperture of 8 in (20 cm) or greater. In a 10 in (25 cm) scope, the granular core shows a diameter of 3′ (arcminutes) surrounded by a 10′ halo of stars.
Messier 28 or M28, also known as NGC 6626, is a globular cluster of stars in the center-west of Sagittarius. It was discovered by French astronomer Charles Messier in 1764. He briefly described it as a "nebula containing no star... round, seen with difficulty in 31⁄2-foot telescope; Diam 2′."
NGC 2477 is an open cluster in the constellation Puppis. It contains about 300 stars, and was discovered by Abbé Lacaille in 1751. The cluster's age has been estimated at about 700 million years.
NGC 6723 is a globular cluster in the constellation Sagittarius. Its magnitude is given as between 6 and 6.8, and its diameter is between 7 and 11 arcminutes. It is a class VII cluster with stars of magnitude 14 and dimmer. It is near the border of Sagittarius and Corona Australis.
The Collinder catalogue is a catalogue of 471 open clusters compiled by Swedish astronomer Per Collinder. It was published in 1931 as an appendix to Collinder's paper On structural properties of open galactic clusters and their spatial distribution.
2MASS-GC02, also known as Hurt 2, is a globular cluster at a distance of about 16 thousand light-years from Earth in the constellation Sagittarius. It was discovered in 2000 by Joselino Vasquez together with globular cluster 2MASS-GC01 and a spiral galaxy 2MASXI J0730080-220105, and confirmed by a team of astronomers under the leadership of R. J. Hurt at 2MASS.
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 6544 is a small globular cluster visible in the constellation Sagittarius. It is magnitude 7.5, diameter 1 arcminute. It is less than 1 degree southeast of Messier 8, the Lagoon Nebula.
NGC 5927 is a globular cluster in the constellation Lupus. NGC 5927 has a diameter of about 12 arcminutes and an apparent magnitude of +8.86. Its Shapley–Sawyer Concentration Class is VIII, and it contains stars of magnitude 15 and dimmer.
NGC 6569 is a globular cluster in the constellation Sagittarius. It has an apparent magnitude of about 9.5, and an apparent diameter of 7 arc minutes, and class VIII with stars of magnitude 15 and dimmer. It is about 2 degrees south east of Gamma2 Sagittarii. The globular cluster was discovered in 1784 by the astronomer William Herschel with his 18.7-inch telescope and was catalogued later in the New General Catalogue.
NGC 6638 is a globular cluster in the constellation Sagittarius. It is magnitude 9.5 and diameter 2 arc minutes, class VI. It is a half degree east of Lambda Sagittarii. It is a member of the Milky Way.
NGC 6528 is a globular cluster in the constellation Sagittarius, and is listed in the New General Catalogue. It has an apparent magnitude of about 11 and a diameter of about 16 arcminutes, and its Shapley-Sawyer Concentration Class is V, containing stars of 16th magnitude and dimmer. Dreyer described it as "pF, cS, R", meaning poor and faint, considerably small and round.
NGC 1436 is a barred spiral galaxy approximately 58 million light-years away from Earth in the constellation of Eridanus. It is a member of the Fornax I cluster.
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 4636 is an elliptical galaxy located in the constellation Virgo. It is a member of the NGC 4753 Group of galaxies, which is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster. It is located at a distance of about 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4636 is about 105,000 light years across.