Radioobservatorier

Radioobservatorier, or radio observatories, are facilities that use radio telescopes to observe celestial radio emissions. They operate across a broad range of frequencies, from tens of megahertz to hundreds of gigahertz, and may rely on a single large dish or an array of antennas to improve sensitivity and angular resolution. Compared with optical astronomy, radio observations reveal cold gas, magnetic fields, and energetic processes that are not visible at optical wavelengths, informing studies of pulsars, the interstellar medium, galaxies, and cosmology.

Instrumentation and methods: Single-dish radiotelescopes collect signals with large parabolic mirrors, while arrays use interferometry to synthesize a larger aperture. Very Long Baseline Interferometry links antennas across continents to achieve milliarcsecond resolution. Data are processed with correlators and software for calibration, imaging, and spectroscopy. Observatories coordinate observing campaigns and maintain public data archives for research and teaching.

History and notable facilities: Radio astronomy began in the 1930s, with subsequent expansion worldwide. Historic sites include Arecibo Observatory (operational 1963–2020, collapsed 2020) and the Parkes Observatory. Active facilities include the Very Large Array (USA), ALMA (Chile), LOFAR (Europe), MeerKAT (South Africa), and FAST (China). The Square Kilometre Array (SKA) is planned as a large international network.

Impact and organization: Radio observatories are run by universities, national agencies, or international consortia. They provide open data, support multi-wavelength programs, and train astronomers. Their work underpins models of galaxy evolution, star formation, magnetic fields, and the physics of compact objects.