The Sombrero Galaxy

Degree of difficulty 3 (of 5)

Minimum aperture 50mm

Designation NGC 4594

Type Galaxy

Class Sa

Distance 44.7 Mly (2003) 27.9 Mly (2001) 31.9 Mly (2001)

Size 105,000 ly

Constellation Virgo

R.A. 12h 40.0min

Decl. –11° 37′

Magnitude 8.0

Surface brightness 20.5mag/arcsec2

Apparent diameter 8,7′×3,5′

Discoverer Méchain, 1781

History M 104 was discovered on the 11th of May 1781, by Pierre Méchain, who noted: “nebula which did not appear to me to contain any single star. It is of a faint light.” Messier knew about Méchain's discovery, since he added a hand-written note of it to his printed copy of his final catalog, and it is likely that he observed this object himself. However, this object came too late to make it into the original catalog. Finally, the well-known French popular astronomy writer Camille Flammarion found Messier's note in 1921 and awarded this galaxy the merits of a Messier object.

William Herschel was able to see much more of M 104 than Méchain. He described it as “A faint diffused oval light” and observed the dark lane bisecting the galaxy. His son John confirmed in 1833 “that there is a dark interval or stratum separating the nucleus and general mass of the nebula from the light above it. Surely no illusion.”

A few years later, Admiral Smyth speculated: “This must be another of those vast flat rings seen very obliquely, already spoken of, and is an elegant example of that celestial perspective.” Heinrich d'Arrest, however, saw just a “bright ray, small nucleus like a star of 10th magnitude.” It took the first deep photographic exposures in the early 20th century to reveal the full beauty of this galaxy. Curtis wrote: “A remarkable, slightly curved, clear-cut dark lane runs along the entire length to the south of the nucleus; probably the finest known example of this phenomenon.