VLBI
Very Long Baseline Interferometry (VLBI) is a radio astronomy technique that combines observations from widely separated antennas to form an effective telescope with a diameter equal to the maximum baseline between stations. By correlating radio signals that are time-stamped with atomic clocks, VLBI attains extremely high angular resolution, often microarcseconds, enabling detailed imaging of compact objects.
Each participating telescope records the incoming radiation along with precise time markers, typically using hydrogen masers.
VLBI has broad applications in astronomy and geodesy. It produces sharp images of active galactic nuclei, quasars,
Typical observing bands include centimeter and millimeter wavelengths, such as L, S, X bands and higher frequencies