Messier 102, Spindle galaxy

Messier 102
Messier 102: Image of NGC 5866 with the Hubble Space Telescope [231]


M 102 was discovered by Pierre Méchain on March 27, 1781 and added to his catalog by Charles Messier. Since the deadline for publication in the «Connoissance» was close to 1784, he had no time to verify the observation as usual. Messier attributed. No. 102: «Nebula between the stars ο in the boat and ι of the dragon: it is very faint, next to it is a star of the sixth magnitude.» [281]

However, the position recorded for M 102 does not correspond to any object that Messier or Méchain could have seen. In a letter dated May 6, 1783, Méchain rejected the discovery and assumed it was merely a renewed observation of M 101. For this reason it was generally assumed for more than 200 years that M 101 and M 102 were the same object, namely the galaxy NGC 5457. The stars ο Boötis and ι Draconis mentioned in the description are 42° apart and therefore not suitable for a position determination. If one assumes that ο Boötis was a misprint should actually be called θ Boötis, this is only 11° away from ι Draconis. In between there are a number of galaxies, only NGC 5866 with 9.8 mag is bright enough that it could have been seen with the telescopes of Méchain and Messier. This was suggested by Camille Flammarion in 1917. [196]

Physical Properties

On Simbad, M 102 is assigned to the galaxy NGC 5866, at NED you land at M 101. M 102 is a lenticular galaxy classified as SA0^+ according to de Vaucouleur. We see them directly from the edge on the central dust band. Heliocentric velocities measurements over the past 20 years range from 672 km/s to 728 km/s and distances from 13 Mpc to 15 Mpc (42 to 49 million light years). The diameter is estimated to be about 70'000 light years and the mass to one trillion solar masses. [145, 196]

«Revised New General Catalogue and Index Catalogue», «Historically Corrected New General Catalogue», Dr. Wolfgang Steinicke, 2021 [277]
NameRADecTypeBmagVmagDimDreyer DescriptionIdentification
NGC 5866 15 06 29.4+55 45 49Gx (S0-a) × 3.1vB, cL, pmE 146°, gbMM 102, UGC 9723, MCG 9-25-17, CGCG 274-16, IRAS 15051+5557
NGC 5866 A15 05 16.1+55 49 39Gx (E0)16.515.50.50 × 0.5vB, cL, pmE 146°, gbMKeeler 690
NGC 5866 B15 12 07.2+55 47 07Gx (SBd) × 1.9vB, cL, pmE 146°, gbMUGC 9769, MCG 9-25-34, CGCG 274-33, KUG 1510+559
NGC 5867 15 06 24.3+55 43 54Gx (C)16.515.50.20 × 0.2eF, vS, stellar
NGC 5870 15 06 33.7+55 28 45S015.414.41.20 × 0.9eF, pS, lE, v diffic, * fNGC 5826, UGC 9725, MCG 9-25-16, CGCG 274-17, IRAS 15053+5540

Finder Chart

The galaxy M 102 is located in the constellation Draco between the stars Edasich (ι Draconis) and Asellus Primus (θ Boötis), about 4° from (ι Draconis. About 1° south of M 102 is the 5.2 mag bright one Star HR 5636, which is still visible to the eye on a clear night The galaxy is circumpolar and is highest in the sky at night from March to September.

Chart M 102
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]


145SIMBAD astronomical database;
149SkySafari 6 Pro, Simulation Curriculum;
160The STScI Digitized Sky Survey;
196Celestial Atlas by Curtney Seligman; (2020-12-28)
231Full ACS image of NGC 5866; (2021-01-17)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; (2021-02-17)
281«Catalogue Nébuleuses et des Amas D'Étoiles» Observées à Paris, par M. Messier, à l'Observatoire de la Marine, hôtel de Clugni, rue des Mathurins. «Connoissance des temps ou connoissance des mouvements célestes, pour l'année bissextile 1784 » Page 227; (2021-02-21)