An Etymological Dictionary of Astronomy and Astrophysics
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1) In radio interferometry, the separation between the electrical, or phase centers of two interferometer elements.
2) In spectroscopy, the contribution to a spectrum from phenomena that are not of astronomical interest, such as frequency dependent properties of the receivers, or by astronomical sources other than those under study.

→ base; → line.

A network of ten 25-m radio telescopes for → very-long-baseline interferometry (VLBI), operated by the U.S. National Radio Astronomy Observatory. Eight of the VLBA telescopes are distributed across the continental United States, while the other two are in Hawaii and the Virgin Islands, giving a maximum baseline of about 8,000 km and a resolution better than a milliarcsecond at its shortest wavelength.

→ very; → large; → baseline; → array.

A technique in radio interferometry in which the individual telescopes are not directly connected together, but instead make their observations separately with very accurate timings. The data are later sent to a central correlator to be combined. With this technique the individual telescopes can be arbitrarily far apart, and so the technique provides the highest resolution images in astronomy, typically down to a few milliarcseconds.

→ very; → large; → baseline; → interferometry.