 Very-long-baseline interferometry

very-long-baseline interferometry correlates accurately time-referenced radio signals recorded at widely separated collectors, giving angular resolution of order wavelength divided by projected baseline. Geometric delays, frequency standards, atmospheric propagation and source structure enter the calibration. Compact maser positions and motions are one application.

Very-long-baseline interferometry (VLBI) is a type of astronomical technique used to achieve high angular resolution imaging of radio sources. It involves the use of multiple radio telescopes located at different geographical locations, often thousands of kilometers apart, which work together to observe the same astronomical object simultaneously.