Angular resolution (by a telescope array)


The highest angular resolutions can be achieved by arrays of telescopes called astronomical interferometers: These instruments can achieve angular resolutions of 0.001 arcsecond at optical wavelengths, and much higher resolutions at radio wavelengths. In order to perform aperture synthesis imaging, a large number of telescopes are required laid out in a 2-dimensional arrangement.

The angular resolution R of an interferometer array can usually be approximated by the following formula.

The resulting R is in radians. Sources larger than the angular resolution are called extended sources or diffuse sources, and smaller sources are called point sources.

For example, in order to form an image in yellow light with a wavelength of 580 nm, for a resolution of 1 milli-arcsecond, we need telescopes laid out in an array.

Related formulas


RAngular resolution R of a telescope array [rad] (dimensionless)
λWavelength of the observed radiation (m)
B length of the maximum physical separation of the telescopes in the array, called the baseline. (m)