Bandwidth smearing is a type of
chromatic aberration
In optics, chromatic aberration (CA), also called chromatic distortion, color aberration, color fringing, or purple fringing, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the ...
(color-related distortion) in the image of a
celestial body
An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ''body'' are of ...
(like a star or galaxy) observed using an
astronomical interferometer
An astronomical interferometer or telescope array is a set of separate telescopes, mirror segments, or radio telescope antennas that work together as a single telescope to provide higher resolution images of astronomical objects such as stars, n ...
(a system combining multiple telescopes to act as one). It is caused by the range of
radio frequencies
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upper ...
(or bandwidth) used in the observation, where, in
Fourier terms, different frequencies capture slightly different spatial details of the object’s shape. This leads to a blurred or stretched appearance in the final image, often with elongated features pointing outward. In
radio astronomy
Radio astronomy is a subfield of astronomy that studies Astronomical object, celestial objects using radio waves. It started in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming from the Milky Way. Subsequent observat ...
, this effect can be reduced by using higher
spectral resolution
The spectral resolution of a spectrograph, or, more generally, of a frequency spectrum, is a measure of its ability to resolve features in the electromagnetic spectrum. It is usually denoted by \Delta\lambda, and is closely related to the resolvi ...
(narrower frequency ranges) or adjusting the image reconstruction process to account for these differences.
References
* Bridle, Alan H. and Schwab, Frederic R., ''Wide Field Imaging I: Bandwidth and Time-Average Smearing'' in ''Synthesis imaging in radio astronomy'' (1989), eds. Richard A. Perley, Frederic R. Schwab, Astronomical Society of the Pacific Conference Series, vol. 6, , p. 247.
{{portal, astronomy
Interferometry