Very Long Baseline Interferometry, VLBI, is used to gain more accurate observations of objects by comparing the information gathered about a single object from multiple locations. The process is based on the same principals shown in the famous Michelson-Morley laser intererometry experiment. Astronomers use VLBI to obtain very accurate observations of extra-terrestrial objects.
In astronomical VLBI, multiple directional attennas are often separated by hundreds of kilometers. The information gathered by each antenna is collected and then cross-correlated to produce a single, more accurate representation of the the observed object. Cross-correlation can occur in real time (if the data can be sent to the correlation point in real time) or off-line (via stored data).
VLBI experiments are being conducted by many groups around the world, including:
- JIVE (Joint Institute for VLBI in Europe)
- Joddrell Bank (England)
- MIT Haystack Observatory (United States)
- EVLBI (European VLBI network)