Messier 102

Messier 102 (also known as M102) is a galaxy listed in the Messier Catalogue that has not been identified unambiguously. Its original discoverer Pierre Méchain later said that it was a duplicate observation of Messier 101,[1] but more recent historical evidence favors that it is NGC 5866,[2] although other galaxies have been suggested as possible identities.

Candidate corresponding objects

Since the publication of the Messier Catalogue, a number of galaxies have been identified by different historians, professional astronomers, and amateur astronomers as corresponding to M102.

Messier 101

M101 hires STScI-PRC2006-10a
Messier 101 as observed by the Hubble Space Telescope. Credit: NASA/ESA.

Messier 101 (also known as the Pinwheel Galaxy or NGC 5457) is a face-on spiral galaxy in the constellation Ursa Major. In a letter written in 1783 to J. Bernoulli, Pierre Méchain (who had shared information about his discoveries with Messier) claimed that M102 was actually an accidental duplication of M101 in the catalog. This letter was later published twice: First in original French in the Memoirs of the Berlin Academy for 1782, and second in German translation and somewhat rearranged by Johann Elert Bode in the Berliner Astronomisches Jahrbuch for 1786.[3][4][5]

NGC 5866

Ngc5866 hst big
NGC 5866 as observed by the Hubble Space Telescope. Credit: NASA/ESA.

NGC 5866 (one of two galaxies commonly called the Spindle Galaxy) is a lenticular galaxy in the constellation Draco. This galaxy appears to closely match both the object description (by Pierre Méchain) in the printed version of the Messier Catalog of 1781, and the object position given by Charles Messier in hand-written notes on his personal list of the Messier Catalogue.[4][5]

Other possible corresponding objects

Although M101 and NGC 5866 are considered to be the two most likely candidates for M102, a few other objects have been suggested as potentially corresponding to this entry.

NGC 5879, NGC 5907, NGC 5908

NGC 5879, NGC 5907, NGC 5905, and NGC 5908 are all galaxies near the position of NGC 5866. By that criterion, they may all be as likely as NGC 5866 to be the objects that correspond to M102. However, none of these galaxies are as bright or as high in surface brightness as NGC 5866, so it is less likely that these objects correspond to M102.[3]

NGC 5928

NGC 5928 is a 14th magnitude galaxy located between ο Boötis and ι Serpentis. J. L. E. Dreyer, in his Notes and Corrections to the New General Catalogue, suggested that this may have been the source identified as M102 on the basis that ι Serpentis may have been misidentified as ι Draconis in the location given for the object.[3][6] However, it may not have been observable by Messier and Méchain, so it is unlikely to correspond to M102.


  1. ^ O'Meara, Stephen James. "M102: Mystery Solved", Sky and Telescope, volume 109, number 3, page 78, March 2005
  2. ^ "Messier 102". Hartmut Frommert. Retrieved 29 December 2016.
  3. ^ a b c K. G. Jones (1991). Messier's Nebulae and Star Clusters (2nd ed.). Cambridge: Cambridge University Press. ISBN 0-521-37079-5.
  4. ^ a b H. Frommert, 2006. "Messier 102: Status der Identifizierung dieses Messier-Objekts" (In German). Journal für Astronomie, No. 19 (I/2006), pp. 69–71 (January 2006)
  5. ^ a b H. Frommert, 1995 to current. Messier 102. An article on the controversy. [1]
  6. ^ J.L.E. Dreyer, New General Catalogue of Nebulæ and Clusters of Stars (1888), Index Catalogue (1895) Second Index Catalogue (1908), Royal Astronomical Society, London, 1971, p.283

External links

List of NGC objects (5001–6000)

This is a list of NGC objects 5001–6000 from the New General Catalogue (NGC). The astronomical catalogue is composed mainly of star clusters, nebulae, and galaxies. Other objects in the catalogue can be found in the other subpages of the list of NGC objects.

The constellation information in these tables is taken from The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer, which was accessed using the "VizieR Service". Galaxy types are identified using the NASA/IPAC Extragalactic Database. The other data of these tables are from the SIMBAD Astronomical Database unless otherwise stated.


M102 may refer to:

Messier 102, an object listed in the Messier Catalogue that remains unidentified

M102 howitzer, an American light-towed 105 mm howitzer

Mercedes-Benz M102 engine, an automobile engine developed by Mercedes-Benz

BMW M102, a BMW piston engine

M-102 (Michigan highway), a highway in Michigan along 8 Mile Road

M102 (New York City bus), a bus route in Manhattan

Messier object

The Messier objects are a set of 110 astronomical objects cataloged by the French astronomer Charles Messier in his Catalogue des Nébuleuses et des Amas d'Étoiles ("Catalogue of Nebulae and Star Clusters").

Because Messier was interested in finding only comets, he created a list of non-comet objects that frustrated his hunt for them. The compilation of this list, in collaboration with his assistant Pierre Méchain, is known as the Messier catalogue. This catalogue of objects is one of the most famous lists of astronomical objects, and many Messier objects are still referenced by their Messier number.

The catalogue includes some astronomical objects that can be observed from Earth's Northern Hemisphere such as deep-sky objects, a characteristic which makes the Messier objects extremely popular targets for amateur astronomers.A preliminary version first appeared in the Memoirs of the French Academy of Sciences in 1771,

and the last item was added in 1966 by Kenneth Glyn Jones, based on Messier's observations.

The first version of Messier's catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45 objects being Messier's.

By 1780 the catalogue had increased to 80 objects. The final version of the catalogue containing 103 objects was published in 1781 in the Connaissance des Temps for the year 1784.

However, due to what was thought for a long time to be the incorrect addition of Messier 102, the total number remained 102. Other astronomers, using side notes in Messier's texts, eventually filled out the list up to 110 objects.The catalogue consists of a diverse range of astronomical objects, ranging from star clusters and nebulae to galaxies. For example, Messier 1 is a supernova remnant, known as the Crab Nebula, and the great spiral Andromeda Galaxy is M31. Many further inclusions followed in the next century when the first addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding Messier's side note in his 1781 edition exemplar 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.

NGC 5866

NGC 5866 (also called the Spindle Galaxy or Messier 102) is a relatively bright lenticular or spiral galaxy in the constellation Draco. NGC 5866 was most likely discovered by Pierre Méchain or Charles Messier in 1781, and independently found by William Herschel in 1788.

Measured orbital velocities of its globular cluster system

imply that dark matter makes up only 34±45% of the mass within 5 effective radii;

a notable paucity.

See also

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