A subclass of the C-class asteroids. Its members have low albedos (0.05–0.09), and are distinguished from class C by having a very strong ultraviolet absorption feature at wavelengths shorter than 0.4 μm caused by water of hydration in the surface material. The largest asteroid, Ceres, is now classified as G class. Other members include (176) Iduna, diameter 121 km, and (640) Brambilla, diameter 81 km.
Subjects: Astronomy and Astrophysics.