“RadioAstron”-A telescope with a size of 300 000 km: Main parameters and first observational results

Abstract

The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna groundspace radio interferometer with extremely long baselines, making it possible for the first time to study various objects in the Universe with angular resolutions a million times better than is possible with the human eye. The project is targeted at systematic studies of compact radio-emitting sources and their dynamics. Objects to be studied include supermassive black holes, accretion disks, and relativistic jets in active galactic nuclei, stellar-mass black holes, neutron stars and hypothetical quark stars, regions of formation of stars and planetary systems in our and other galaxies, interplanetary and interstellar plasma, and the gravitational field of the Earth. The results of ground-based and inflight tests of the space radio telescope carried out in both autonomous and ground-space interferometric regimes are reported. The derived characteristics are in agreement with the main requirements of the project. The astrophysical science program has begun.

Space-based aperture array for ultra-long wavelength radio astronomy

“…Along similar lines, lunar orbiting singlesatellite missions dedicated for radio astronomy such as LORAE [22] and DARE [24] were also investigated to map bright sources and to facilitate relatively easier Earth-based down-link of science data. Furthermore, the pursuit of higher angular resolutions has led to Earth-orbiting single-satellite missions such as HALCA [32] and Radio Astron [38] which enable Earth-space very long baseline interferometry [31].…”

The RadioAstron Dedicated DiFX Distribution

“…In the following, a list of the modifications and capabilities already present in the first branch is given: Consistency checks with the ASC correlator ( [3]) have been performed at an initial stage (2013), by means of the correlation of a number of experiments with both pieces of software and comparing results. These have shown to be compatible within errors [5].…”

“…It is a 10-m single dish, mounted onboard the Spekt-R satellite, and is able to perform interferometry observations with ground arrays of radio telescopes [3]. It can reach extreme baselines of ∼25 Earth diameters, thanks to an elliptical orbit with an apogee of ∼330.000 km-almost the distance between Earth and the Moon.…”

Radio Pulsars

“…The radio emission regions of pulsars lie within the light cylinder, and so have angular sizes from Earth of nanoarcseconds or less. Resolving such an angle at radio wavelengths requires an instrument with an aperture approaching an AU, beyond the capabilities of even the longest VLBI baselines (Kardashev et al 2013). However, radio-wave scattering by the dilute, turbulent interstellar plasma yields the required angular resolution and offer some of the information provided by a lens of that aperture.…”