Using Phase Dynamic Cross-Spectra for Wideband Radio Astronomy Observations: Experience from the UTR-2 Radio Telescope

Abstract

Dynamic spectra characterize the distribution of the total power of the received signal over time and frequency. They are widely used in radio astronomy in analysis of observations. The paper describes a method that expands capabilities of such a time-frequency analysis via utilization of the phase difference between signals from two subantennas which are formed within the entire radio telescope antenna system. Phase dynamic spectra – the phase of the cross-spectrum of two signals as function of time and frequency – are formed by interferometric processing. Then, they are used for analysis together with the traditional dynamic spectra of power. This technique was implemented at the UTR-2 radio telescope. It has been used there for several years for visual detection of radio emission, for recognition of the interfering signals arriving from the antenna side lobes, as well as for differentiation of radio bursts observed within the main beam. If two pairs of antennas with noncollinear baselines are available, then the direction of arrival can be measured at each point of the time–frequency domain from the two phase dymamic spectra. The efficiency of this technique is illustrated by its application to qualitatively different types of sporadic radio emisson – namely, the emission of the Sun, Saturn, and flare stars.