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

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

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

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

Multi-antenna observations in the low-frequency radio astronomy of solar system objects and related topics studies

International audienceRapid 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

The modern radio astronomy network in Ukraine: UTR-2, URAN and GURT

International audienceThe current status of the large decameter radio telescope UTR-2 (Ukrainian T-shaped Radio telescope) together with its VLBI system called URAN is described in detail. By modernization of these instruments through implementation of novel versatile analog and digital devices as well as new observation techniques, the observational capabilities of UTR-2 have been substantially enhanced. The total effective area of UTR-2 and URAN arrays reaches 200 000 m2, with 24 MHz observational bandwidth (within the 8-32 MHz frequency range), spectral and temporal resolutions down to 4 kHz and 0.5 msec in dynamic spectrum mode or virtually unlimited in waveform mode. Depending on the spectral and temporal resolutions and confusion effects, the sensitivity of UTR-2 varies from a few Jy to a few mJy, and the angular resolution ranges from ~ 30 arcminutes (with a single antenna array) to a few arcseconds (in VLBI mode). In the framework of national and international research projects conducted in recent years, many new results on Solar system objects, the Galaxy and Metagalaxy have been obtained. In order to extend the observation frequency range to 8-80 MHz and enlarge the dimensions of the UTR-2 array, a new instrument - GURT (Giant Ukrainian Radio Telescope) - is now under construction. The radio telescope systems described herein can be used in synergy with other existing low-frequency arrays such as LOFAR, LWA, NenuFAR, as well as provide ground-based support for space-based instruments