Digital receivers for low-frequency radio telescopes UTR-2, URAN, GURT

This paper describes digital radio astronomical receivers used for decameter and meter wavelength observations. This paper describes digital radio astronomical receivers used for decameter and meter wavelength observations. Since 1998, digital receivers performing on-the-fly dynamic spectrum calculations or waveform data recording without data loss have been used at the UTR-2 radio telescope, the URAN VLBI system, and the GURT new generation radio telescope. Here we detail these receivers developed for operation in the strong interference environment that prevails in the decameter wavelength range. Data collected with these receivers allowed us to discover numerous radio astronomical objects and phenomena at low frequencies, a summary of which is also presented.Comment: 24 pages, 15 figure

Study of SED's emission parameters

International audienceThe present research is devoted to the study of parameters of Saturn Electrostatic Discharges (SED) according to the data obtained during the observations of the initial period of storm J (December 2010) or the so-called Great White Spot (GWS). The ground-based detection was provided by the Ukrainian radio telescope UTR-2 at frequencies from 8 to 33 MHz in a wide range of time scales: from the day-to-day SED investigations to the temporal fine structure study up to microseconds. In this paper we describe our methods of data cleaning and the search for Saturn lightning in detail. The sensitivity of the observations allowed us to resolve the temporal micro-structure of lightning discharges. We determined the average signal's dispersion delay for a session equal to (4.4 +- 0.8)*10^{-5} pc cm^{-3}. It is close to the predicted value along the ray path from the storm to the radio telescope

STUDY OF SATURN ELECTROSTATIC DISCHARGES IN A WIDE RANGE OF TIME SCALES

Saturn Electrostatic discharges (SED) are sporadic broadband impulsive radio bursts associated with lightning in Saturnian atmosphere. After 25 years of space investigations in 2006 the first successful observations of SED on the UTR-2 radio telescope were carried out [1]. Since2007 along-term program of ED search and study in the Solar system has started. As a part of this program the unique observations with high time resolution were taken in 2010.New possibilities of UTR-2 radio telescope allowed to provide a long-period observations and study with high temporal resolution. This article presents the results of SED study in a wide range of time scales: from seconds to mi­croseconds. For the first time there were obtained a low frequency spectrum of SED. We calculated flux densities of individual bursts at the maximum achievable time resolu­tion. Flux densities of most intensive bursts reach 4200 Jy.

Solar system radio emissions studies with the largest low-frequency radio telescopes

International audienceWe describe the trends and tasks in the field of lowfrequency studies of radio emission from the Solar system's objects. The world's largest decameter radio telescopes UTR-2 and URAN have a unique combination of sensitivity and time/frequency resolution parameters, providing the capability of the most detailed studies of various types of solar and planetary emissions

Solar system radio emissions studies with the largest low-frequency radio telescopes

International audienceWe describe the trends and tasks in the field of lowfrequency studies of radio emission from the Solar system's objects. The world's largest decameter radio telescopes UTR-2 and URAN have a unique combination of sensitivity and time/frequency resolution parameters, providing the capability of the most detailed studies of various types of solar and planetary emissions

Multi-antenna observations in the low-frequency radio astronomy of solar system objects and related topics studies. Planetary Radio Emissions|PLANETARY RADIO EMISSIONS VIII 8|

Rapid progress currently takes place in the field of low-frequency radio astronomy in the meter–decameter–hectometer range of wavelengths. It is caused by a radical modernization of the existing radio telescopes, creation of a new generation of instruments, space-borne observations, and by the development of research on all classes of astrophysical objects, including the Solar System. On the other hand, a range of difficulties specific to low-frequency radio astronomy is known, which are caused by technical, methodological, and physical limitations. An effective strategy for overcoming these difficulties is based on synchronous observations using several radio telescopes separated by distances from a few to several thousand kilometers. This provides an opportunity to reduce and identify radio interference and the influence of the propagation media, to increase the sensitivity and resolution, and to solve many problems with higher efficiency. In recent years such simultaneous observations were carried out for the Sun, Jupiter, Saturn, interplanetary medium, pulsars, exoplanets, and transients using the radio telescopes UTR-2, URAN, GURT, NDA, NenuFAR, LOFAR and other. Parallel observations with the space missions WIND, STEREO, Cassini and Juno also facilitate improvement of the quality and reliability of low-frequency radio astronomical experiments

SPORADIC RADIO EMISSION OF SPACE OBJECTS AT LOW-FREQUENCIES

International audiencePurpose: The results of studies of sporadic radio emission of several types of space radio sources, including neutron stars and planets of the Solar System, are presented. The aim of this work is to review the latest achievements in the study of low-frequency radio emission of the Solar System planets and transient signals similar to pulsar pulses using the UTR-2 radio telescope. The importance of the development of the verification methods of the spaceborne radio emission in the study of sporadic signals from various sources is shown. Design/methodology/approach: The studies of sporadic signals of different nature are based on the common set of procedures for cleaning records from the terrestrial radio frequency interference (RFI) in the frequency-time pattern using the information on the nature of the particular type of sporadic radio emission, possible types of interference and signal distortion. Characteristic features of sporadic radio emission of different sources are given, and for each of them the optimal method of signal extraction is developed. The efficiency of the developed procedures for cleaning from noise using adjustable parameters is shown. This is done on the basis of observations of diverse types of space radio sources, such as lightnings in the atmospheres of planets, single pulses of neutron stars and sporadic radio emission of Jupiter. Findings: The developed methods of signal extraction detection in the presence of radio-interference have allowed obtaining the unique results such as: the distribution of the total intensity of single pulses of neutron stars depending on the galactic latitude; the automatic search of lightnings in the Saturn’s atmosphere in data due to the carefully elaborated RFI mitigation procedures, which made it possible to obtain the Saturn electrostatic discharge (SED) emission parameters based on the most complete set of events. Increased efficiency of the selection of Jupiter’s S-radiation signals despite the data corruption by the presence of radio-interference, which was reached due to the carefully chosen parameters of data cleaning procedures, have allowed us to detect short and intensive bursts, being the most informative for determining the physical parameters of radio emission in the area of their generation. Conclusions: The large effective area and high sensitivity of the UTR-2 radio telescope allow making the sporadic radio emission study with high temporal and frequency resolutions. Due to these factors we can apply a wide range of methods of space signals’ detection in the presence of terrestrial radio-frequency interference of natural and artificial origin. The data cleaning parameters allow accounting for the characteristic features of space signals and to obtain important and even unique scientific results. Key words: decameter wavelength range; UTR-2; sporadic radio emission; transients; lightning in the atmospheres of planets; Jupiter S-burst

Identification of Saturn Lightnings Recorded by the UTR-2 Radio Telescope and Cassini Spacecraft

International audienceThe Saturn electrostatic discharges (SED) simultaneously recorded in the initial period of storm F at the UTR-2 radio telescope and Cassini spacecraft are investigated. The UTR-2 used the FFT-spectral receiver operating 12÷33 MHz, while the Cassini the serial spectrum analyser RPWS (Radio Plasma Wave Science) operating 1.8÷16 MHz. The ground and space data processed have shown very good agreement. E-folding time of SED and its dependence on episode intensity in the initial period of storm F were determined

Astrophysical Studies with Small Low-Frequency Radio Telescopes of New Generation

International audienc

Identification of Saturn Lightnings Recorded by the UTR-2 Radio Telescope and Cassini Spacecraft

International audienceThe Saturn electrostatic discharges (SED) simultaneously recorded in the initial period of storm F at the UTR-2 radio telescope and Cassini spacecraft are investigated. The UTR-2 used the FFT-spectral receiver operating 12÷33 MHz, while the Cassini the serial spectrum analyser RPWS (Radio Plasma Wave Science) operating 1.8÷16 MHz. The ground and space data processed have shown very good agreement. E-folding time of SED and its dependence on episode intensity in the initial period of storm F were determined