ShortBaseline

Short baseline refers to a relatively short separation between individual apertures or antennas in an interferometric array. In interferometry, the angular resolution achievable by a pair of elements is approximately the observing wavelength divided by the baseline length. Therefore, short baselines yield lower angular resolution but are crucial for sampling larger angular scales on the sky. The exact meaning of "short" is context-dependent, varying with the observing wavelength and the array design.

Short baselines play a key role in capturing extended emission that would be resolved out by longer baselines. They sample the central region of the Fourier domain, or uv-plane, which contains information about large-scale structure. Missing these short spacings can lead to missing flux in images and distortions of extended features. To mitigate this, astronomers combine interferometric data with total-power measurements from single-dish telescopes or use dedicated short-baseline configurations to recover the full range of spatial frequencies.

In practice, arrays are often configured with a mix of short and long baselines to balance sensitivity to extended emission with the ability to resolve fine detail. Data from different baseline ranges are processed together, using imaging and deconvolution algorithms that incorporate prior information to reconstruct accurate maps. Techniques such as mosaicking and joint deconvolution help improve coverage of the uv-plane and improve fidelity for extended sources.

The concept of short baseline is widely used across interferometry disciplines, including radio and optical/infrared astronomy. It is essential for studies of diffuse gas, molecular clouds, nearby galaxies, and other sources with substantial large-scale structure, enabling a more complete representation of the observed sky.