THE LONG-TERM OBSERVATIONS OF THE POWER COSMIC RADIO SOURCES ON THE RADIO TELESCOPE URAN-4 AT THE DECAMETER WAVE RANGE

Abstract

The radio telescope (RT) URAN-4, located near the city of Odessa, started to work in 1987 as a component of the radio interferometric system URAN, which operates in the decameter range of radio waves and whose elements are placed in several points throughout Ukraine. The first successful VLBI observations of compact cosmic radio sources in the URAN system were carried out on the RT URAN-4–UTR-2 interferometer at the end of 1987. In the same period, a program was launched for regular observations of powerful cosmic radio sources 3C 144, 3C 274, 3C 405, 3C 461 at frequencies of 20 and 25 MHz in the radiometric mode. Later, several stages of modernization of radiometric equipment and systems for automation of observations took place. This made it possible by 2000 to switch to practically continuous radiometric monitoring of a group of these radio sources. Method of measuring and processing of the records of the radio sources passage through RT direction pattern, statistics of the observation records on time periods in dependence on the registration systems of the data obtained during more 35 years observations on the RT URAN-4 are considered in this paper. Some results are given which related to the study of the flux densities of the observing radio sources and ionospheric scintillation effect which is essential at the decameter wavelength range.