In the latest issue of Astronomy and Astrophysics:
Photometric and spectroscopic observations of (132524) 2002 JF56: fly-by target of the New Horizons mission
QUOTEFrom ground-based observations (132524) 2002 JF56 is classified as an S-type asteroid. The axis-ratio determined shows that during the time of observation no large changes of the asteroidís cross-section took place. The estimated effective diameter is in agreement with that obtained by the New Horizons mission (approximately 2.5 km) observations (http://pluto.jhuapl.edu/gallery/missionPho...s/asteroid.html). A determination of the rotational period may be possible by combining set of photometric data from different observers.