We have used the 2dF spectrograph on the Anglo-Australian Telescope to obtain a complete spectroscopic sample of all objects in the magnitude range , 16.5 < b _ { J } < 19.8 , regardless of morphology , in an area centred on the Fornax Cluster of galaxies .
Among the unresolved targets are five objects which are members of the Fornax Cluster .
They are extremely compact stellar systems with scale lengths less than 40 parsecs .
These ultra-compact dwarfs are unlike any known type of stellar system , being more compact and significantly less luminous than other compact dwarf galaxies , yet much brighter than any globular cluster .