First Very Long Baseline Observations performed by ALMA
ALMA, the Atacama Large Millimeter/submillimeter Array, has successfully combined its immense collecting area and sensitivity with that of APEX (Atacama Pathfinder Experiment) to create a new, single instrument through a process known as Very Long Baseline Interferometry (VLBI).
Larger telescopes can make sharper observations, and interferometry allows multiple telescopes to act like a single telescope as large as the separation — or baseline — between them. In VLBI, data from two independent telescopes are combined to form a virtual telescope that spans the geographic distance between them — potentially up to the diameter of the Earth — yielding extraordinary magnifying power.
— Official Announcement