Interferometry with decametric waves (review)

Very-long-baseline interferometers are now used for astrophysical high-frequency observations and measurements using centimetric and metric waves. Interferometry with decametric waves would be more suitable for exploration of regions with small angular dimensions or with steep spectra such as found in stellar relicts, at frequencies below 50 MHz. Use of decametric waves is still problematic, however, because of the terrestrial ionosphere which influences long-wave interferometry through the mechanisms of Faraday rotation, phase shift, and flicker. These effects were studied and their magnitudes measured with a URAN-1 interferometer using the north-south antenna array of a UTR-2 radiotelescope. On the basis of the data and their statistical analysis, procedures for measuring the visibility function of sources with shorter waves were modified for use of longer waves. Radioemission from Jupiter and the nebula in Cancer served as most suitable objects for developing and testing these procedures.