Messier object

Messier object

Messier objects, taken and compiled by an amateur astronomer
Alternative names Messier Catalogue
Survey type astronomical catalog
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Target nebula, planetary nebula, open cluster, globular cluster, galaxy
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Named after Charles Messier
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Published 1771
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Band visual perception
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The Messier objects [me.sje] are a set of over 100 astronomical objects first listed by French astronomer Charles Messier in 1771.[1] Messier was a comet hunter, and was frustrated by objects which resembled but were not comets, so he compiled a list of them,[2] in collaboration with his assistant Pierre Méchain, to avoid wasting time on them. The number of objects in the lists he published reached 103, but seven more thought to have been observed by Messier have been added by other astronomers over the years.

A similar list had been published in 1654 by Giovanni Hodierna, but attracted attention only recently and was probably not known to Messier.[3]

Lists and editions

The first edition covered 45 objects numbered M1 to M45. The total list published by Messier finally contained 103 objects, but the list was expanded through successive additions by other astronomers, motivated by notes in Messier’s and Mechain’s texts indicating that at least one of them knew of the additional objects. The first such addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding a note Messier made in a copy of the 1781 edition of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.[4] M102 was observed by Méchain, who communicated his notes to Messier. Méchain later concluded that this object was simply a re-observation of M101, though some sources suggest that the object Méchain observed was the galaxy NGC 5866 and identify that as M102.

Messier's final catalogue was included in the Connaissance des Temps for 1784 (published in 1781).[5][6] These objects are still known by their "Messier number" from this list.

Messier lived and did his astronomical work at the Hôtel de Cluny (now the Musée national du Moyen Âge), in France. The list he compiled contains only objects found in the sky area he could observe: from the north celestial pole to a celestial latitude of about −35.7°. He did not observe or list objects visible only from farther south, such as the Large and Small Magellanic Clouds.

Observations

The Messier catalogue comprises nearly all the most spectacular examples of the five types of deep-sky object – diffuse nebulae, planetary nebulae, open clusters, globular clusters, and galaxies – visible from European latitudes. Furthermore, almost all of the Messier objects are among the closest to Earth in their respective classes, which makes them heavily studied with professional class instruments that today can resolve very small and visually spectacular details in them. A summary of the astrophysics of each Messier object can be found in the Concise Catalog of Deep-sky Objects.[7]

Since these objects could be observed visually with the relatively small-aperture refracting telescope (approximately 100 mm, or 4 inches) used by Messier to study the sky, they are among the brightest and thus most attractive astronomical objects (popularly called deep-sky objects) observable from Earth, and are popular targets for visual study and astrophotography available to modern amateur astronomers using larger aperture equipment. In early spring, astronomers sometimes gather for "Messier marathons", when all of the objects can be viewed over a single night.[8]

See also

References

  1. ↑ "Charles Messier's Catalog of Nebulae and Star Clusters". SEDS. 12 August 2011. Retrieved 2014-05-17.
  2. ↑ "The Messier Catalog". SEDS Messier Database. SEDS. 25 February 2008. Retrieved 2010-05-08.
  3. ↑ Birthday of a star cluster, Astronomy Now, January 2011, page 20.
  4. ↑ Patrick Moore (1979). The Guinness Book of Astronomy. Guinness Superlatives. ISBN 0-900424-76-1.
  5. ↑ Charles Messier (1781). "Catalogue des Nébuleuses & des amas d'Étoiles". Connaissance des Temps for 1784. pp. 227–267.
  6. ↑ "Original Messier Catalog of 1781". Original Messier Catalog of 1781. SEDS. Retrieved 2014-05-17.
  7. ↑ W.H. Finlay (2003). Concise Catalog of Deep-sky Objects: Astrophysical Information for 500 Galaxies. Springer. ISBN 1-85233-691-9.
  8. ↑ "The Messier Marathon". SEDS. 19 March 2013. Retrieved 2014-05-17.
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