Degree of difficulty 4 (of 5)

Minimum aperture 50mm

Designation NGC 205

Type Galaxy

Class dSph Irr

Distance 2.57 Mly (see M 31) 2.82 Mly (PN, 2000)

Size 16,000 ly

Constellation Andromeda

R.A. Oh 40.4min

Decl. +41° 41′

Magnitude 8.0

Surface brightness 22.8mag/arcsec2

Apparent diameter 21,9′×11,0′

Discoverer Messier, 1773

History M 110 was discovered by Charles Messier on the 10th of August 1773, but it never occurred to him to include it in his catalog. Almost thirty years after his initial observation, he finally published the following note in the Connaissances des Temps, 1801: “On the 10th of August, 1773, I studied the beautiful nebula in the girdle of Andromeda (No. 31) under a very good sky, using my achromatic refractor with a 68× magnification, in order to produce a drawing like the one for the nebula in Orion. I saw the nebula which LeGentil had discovered on Oct. 29, 1749 (No. 32). In addition, I saw a new, fainter situated north of the large one. It seemed unbelievable to me, that the faint nebula would not have been noticed by astronomers and myself since the discovery of the large one by Simon Marius in 1612, since the small one is in the same field of the telescope when observing the large one.” Finally, it was Kenneth Glyn Jones, in 1966, who suggested making this galaxy the last addition to the Messier catalogue, as No. 110.

An independent discovery of M 110 was made by Caroline Herschel on the 27th of August 1783. Her brother William then described her object as “a very considerable, broad, pretty faint, small nebula. It shows the same faint color as the great one, and is, no doubt, in the neighbourhood of it.” Admiral Smyth characterized M 110 in 1836 as “a large faintish nebula of an oval form,” and Reverend Webb wrote: “Large faint oval nebula, best with low powers, a very large field includes it with M 32 and M 31. Seems to sparkle.”