204 Kallisto is a fairly typical, although sizeable Main belt asteroid. It is classified as an S-type asteroid. Like other asteroids of its type, it is light in colour. It was discovered by Johann Palisa on 8 October 1879, in Pola, and was named after the same nymph Callisto in Greek mythology as Jupiter's moon Callisto.
Photometric measurements during 2009 produced a lightcurve that indicated a sidereal rotation period of with a variation amplitude of magnitudes. This result conflicted with previous determinations of the period, so the latter were ruled out.
Notes
References
External links The Asteroid Orbital Elements Database Minor Planet Discovery Circumstances
Asteroid Albedo Compilation