This view of the dark side of Vesta was taken from a distance of about 3,200 miles.
NASA describes the instruments brought aboard Dawn:
"In addition to the framing camera, Dawn's instruments include the gamma ray and neutron detector and the visible and infrared mapping spectrometer. The gamma ray and neutron detector uses 21 sensors with a very wide field of view to measure the energy of subatomic particles emitted by the elements in the upper yard (meter) of the asteroid's surface. The visible and infrared mapping spectrometer will measure the surface mineralogy of both Vesta and Dawn's next target, the dwarf planet Ceres."
Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA