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

A low-noise, high-dynamic-range, digital receiver for radio astronomy applications: an efficient solution for observing radio-bursts from Jupiter, the Sun, pulsars, and other astrophysical plasmas below 30 MHz

International audienceA new two-channel digital receiver that can be used for observing both stationary and sporadic radio sources in the decameter wave band is presented. Current implementation of the device operating at the sampling frequency of 66 MHz is described in detail, including the regimes of waveform capture, spectrogram analysis, and coherence analysis (cross covariance between the two inputs). Various issues pertaining to observational methods in the decameter waveband affected significantly by man-made interferences have been taken into account in the receiver design, as well as in the architecture of the interactive software that controls the receiver parameters in real time. Two examples of using the receiver with the UTR-2 array (Ukraine) are reported: S-bursts from Jupiter and low-frequency wide-band single pulses from the pulsar PSR0809+7

Ground-based and spacecraft observations of lightning activity on Saturn

International audienceIn late 2007, Saturn electrostatic discharges (SED) were simultaneously observed at the radio telescope UTR-2 and with the Cassini spacecraft. Observations at UTR-2 were performed with a multichannel receiver in the frequency range 12-33MHz, and those performed on Cassini-with a swept frequency receiver that is part of the RPWS (Radio and Plasma Wave Science) instrument in the frequency band 1.8-16MHz. We got a very good coincidence between data of UTR-2 and Cassini. It is shown for the first time that ground-based radio astronomy lets us detect Saturn's lightning with a high degree of reliability despite terrestrial interferences. This is the necessary basis for further detailed study of the temporal and spectral characteristics of the SEDs with ground based radio telescopes. Based on six observation sessions, several parameters of SEDs were determined, in particularly a correlation of 0.77 ± 0.15 between the average intensity of storms and the e-folding time. [All rights reserved Elsevier]

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

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