C40

Part of a crowd of faint galaxies within the boundaries of Leo, C40 lies in the eastern parts of the constellation, within the body of the Lion. In the skies of Earth, it falls between the naked-eye stars Zosma to the north and Chertan to the south. It belongs the NGC 3607 Group, which itself is part of a larger network of galaxy groups, the Leo II Groups, filling this area of the sky.

Structurally, C40 belongs to the class of galaxies known as 'lenticular'. Like a spiral galaxy, it consists of a circular disc and central bulge, but unlike a more typical spiral galaxy, it possesses no distinct spiral arms. Within the central regions of the galaxy, a complex band of dark dust forms a ring around the nucleus. The entire galaxy is some 55,000 light years across (that is, a little over half the diameter of the Milky Way Galaxy), and lies approximately seventy million light years from the Milky Way.

C40 appears with two different catalogue numbers in New General Catalogue: NGC 3626 and NGC 3632. After it was first discovered in John Herschel in 1784, its position was slightly miscalculated, and only later corrected by his sister Caroline. This was relevant to its numbering, because NGC numbers are assigned based on an object's right ascension on the celestial sphere. Thus the original designation NGC 3632 was corrected to NGC 3626 (and indeed some catalogues now list the original NGC 3632 as referring to a non-existent object).