Angular structure of extragalactic radio sources at low frequencies

The low frequency VLBI of URAN network operated in the decameter range has been designed in Ukraine to study cosmic radio sources. The network consists of five radio telescopes making up of four interferometers with baselines range from 42 to 913 km with UTR-2 radio telescope operated as the main antenna of the interferometers. The angular resolution of the network amount to 1 arcsec at the highest frequency of the range, and its sensitivity is about 20 Jy. Regular observations of galactic and extragalactic radio sources are performed with the network. Some results of studies are presented here

Research of the fine structure of the radio galaxy 3C 234 with radio interferometer URAN-2

The brief description and the basic characteristics of the radio interferometer URAN-2 aerial system, included in VLBI decameter system URAN, are presented. The research results of the 3C 234 angular structure with URAN system are submitted. The model of radiobrightness distribution of this source at frequencies of 20 and 25 MHz is obtained. With the URAN-2 radio interferometer compact details in a radio galaxy have been found and their contribution to the general flow of a radio emission at decameter waves is determined. The effect of reabsorption in compact details (hot spots) is found and their true angular size are determined based on the research of the 3C234 spectrum

New decameter radiopolarimeter URAN-2

The description of the new decameter radiopolarimeter is submitted. It is created based on the phased array URAN-2, which is the greatest decameter array in the world after UTR-2, having the effective area about 30 000 m2, consisting of 512 broadband dipoles and working at frequencies from 10 up to 30 MHz. Polarimeter works at the central frequency of 24.75 MHz in a band of 10 kHz and 0.3 kHz. It provides reception of circular polarization waves by the horizontal crossed dipoles from any direction. Its sensitivity is ≈100 Jy. With the URAN-2 radiopolarimeter polarizing characteristics of a sporadic radio emission of the Sun (bursts of II and III types), and Jupiter (L- and S-bursts) are investigated. The obtained data will consist well with the results derived in adjacent frequency ranges. At research of the radio emission of Cyg A and Cas A the essential fluctuations of a degree of circular polarization (Stokes V parameter) of these sources radiations are found. This is caused, presumably, by ionosphere inhomogeneity. It is unique radiopolarimeter really working on so low frequencies. The URAN-2 radiopolarimeter organically supplements unique Ukrainian system of URAN decameter radio telescopes