A huge, low surface brightness galaxy, about 1 billion l.y. away in the constellation Coma Berenices. It has a diameter of nearly 600 000 l.y. and a total mass of over 2 × 1012 solar masses, but the gas-rich disk is so faint that it was discovered only in 1986 on specially processed photographic plates by the British astronomer David Frederick Malin (1941– ).