ABSTRACT Oscillations of decameter type IV bursts were registered during observations of solar ra... more ABSTRACT Oscillations of decameter type IV bursts were registered during observations of solar radio emission by UTR-2, URAN-2 and NDA in 2011-2012. Large majority of these bursts were accompanied by coronal mass ejections (CMEs), which were observed by SOHO and STEREO in the visible light. Only in some cases decameter type IV bursts were not associated with CMEs. The largest periods of oscillations P were some tens of minutes. There were some modes of long periods of oscillations simultaneously. Periods of oscillations in flux and in polarization profiles were close. Detailed properties of oscillations at different frequencies were analyzed on the example of two type IV bursts. One of them was observed on April 7, 2011 when a CME happened. Another one (August 1, 2011) was registered without any CME. The 7 April type IV burst had two periods in the frames 75-85 and 35-85 minutes. Interesting feature of these oscillations is decreasing periods with time. The observed decreasing rates dP/dt equaled 0.03-0.07. Concerning type IV burst observed on August 1, 2011 the period of its oscillations increases from 17 min. at 30 MHz to 44 min. at 10 MHz. Connection of type IV burst oscillations with oscillations of magnetic arches and CMEs at corresponding altitudes are discussed. The work is fulfilled in the frame of FP7 project "SOLSPANET".
In the present paper an analysis of the polarization properties of the solar decameter spikes is ... more In the present paper an analysis of the polarization properties of the solar decameter spikes is performed. We found that decameter spikes can possess both left and right circular polarization which changes from 0 up to 100% with an average value 50%.status: publishe
Purpose: A historical review of the experimental baselopment of low-frequency radio astronomy in ... more Purpose: A historical review of the experimental baselopment of low-frequency radio astronomy in Ukraine, its foundation half a century ago by an outstanding scientist S.Ya. Braude to the current state. Design/methodology/approach: The constant progress of electronic, computer and digital technologies, information and telecommunication technologies, theory and practice of antenna and receiving systems design, which introduction enriched the hardware and methodological ideology of construction and usage of the UTR-2, URAN, and GURT radio telescopes, have been used. Findings: The worldwide most effective national experimental radio astronomy means, the UTR-2, URAN, and GURT decameter-meter wave radiotelescopes, have been created and improved. The best combination of the systems main parameters: sensitivity; frequency band; spatial, frequency and temporal resolutions; noise immunity; uniformity of amplitude-frequency and space-frequency characteristics and multifunctionality has been p...
ABSTRACT Results of study of the continuum radio emission of the Sun in the decameter range are p... more ABSTRACT Results of study of the continuum radio emission of the Sun in the decameter range are presented. Observations were carried out with radio telescope URAN-2 in summer months in 2008-2009. Radio fluxes at frequencies 20 MHz and 25 MHz in frequency band 250 kHz were obtained during the time, when there were no active regions on the solar disk. Their average values for two years were 670 Jy and 850 Jy at frequencies 20 MHz and 25 MHz correspondingly. These fluxes are in agreement with high frequency values.
Two CME's (coronal mass ejections)were registered by SOHO and STEREO on April 2, 2011. The re... more Two CME's (coronal mass ejections)were registered by SOHO and STEREO on April 2, 2011. The results of observations, obtained by radio telescope URAN-2 of different CME manifestations in radio emission at the decameter wavelengths are discussed in the present paper. Particularly, it is reported about registration of a new type of fine structure of type II bursts.
This paper describes digital radio astronomical receivers used for decameter and meter wavelength... more 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.
Cutting edge astrophysical studies require more and more observing time at low-frequency radio te... more Cutting edge astrophysical studies require more and more observing time at low-frequency radio telescopes, which is limited and quite expensive. Modern digital signal processing systems still unable to provide affordable computational and storage resources to allow simultaneous beamforming in a wide frequency range for multiple studies. Low-frequency radio telescopes of a new generation are very flexible and could be split into subarrays or groups of subarrays for some studies which do not require large antenna effective area and high directivity. In this paper we make a survey of astrophysical studies in the frequency range 8–80 MHz using a rather small part of the low-frequency radio telescope GURT - the subarray of 25 active antennas.
Рассмотрены характеристики всплеска II типа с “елочной” структурой, который наблюдался 7 июня 201... more Рассмотрены характеристики всплеска II типа с “елочной” структурой, который наблюдался 7 июня 2011 г. в полосе частот 3÷33 МГц как наземными радиотелескопами (УТР-2, УРАН-2), так и космическими аппаратами (“СТЕРЕО”). Впервые в декаметровом диапазоне проведен статистический анализ основных параметров субвсплесков “елочной” структуры всплеска II типа (длительности и модуля скорости частотного дрейфа) отдельно для субвсплесков с положительным и отрицательным частотным дрейфом. Впервые также в этом диапазоне выполнена оценка степе- ни круговой поляризации тонкой структуры всплеска II типа. Обнаружена тонкая частотная структура “елочных” субвсплесков, которая по параметрам оказалась близкой к “бахроме”, наблюдающейся у солнечных S-всплесков. По характерному волнообразному изменению частоты “ствола” всплеска определены параметры корональных стри- меров, пересекаемых фронтом ударной волны. По данным наблюдений космических аппаратов “СТЕРЕО” и “СОХО” найдены направление и скорость распростр...
From 25 June till 12 August 2011 sporadic solar radio emission was observed simultaneously by thr... more From 25 June till 12 August 2011 sporadic solar radio emission was observed simultaneously by three separate radio telescopes: UTR-2 (Kharkov, Ukraine), URAN-2 (Poltava, Ukraine) and NDA (Nancay, France). During these observations several type II bursts with double and triple harmonics were registered, as well as type II bursts with complex herringbone structure. The events of particular interest were type II bursts registered on 9 and 11 August 2011. These bursts had opposite sign of circular polarization at different parts of their dynamic spectra. In our opinion we registered the emissions, which came from the different parts of the shock propagating through the solar corona. We have observed also groups of type III bursts merged into one burst, type III bursts with triple harmonics and type III bursts with "split" polarization. In addition some unusual solar bursts were registered: storms of strange narrow-band (up to 500kHz) bursts with high polarization degree (about...
ABSTRACT Oscillations of decameter type IV bursts were registered during observations of solar ra... more ABSTRACT Oscillations of decameter type IV bursts were registered during observations of solar radio emission by UTR-2, URAN-2 and NDA in 2011-2012. Large majority of these bursts were accompanied by coronal mass ejections (CMEs), which were observed by SOHO and STEREO in the visible light. Only in some cases decameter type IV bursts were not associated with CMEs. The largest periods of oscillations P were some tens of minutes. There were some modes of long periods of oscillations simultaneously. Periods of oscillations in flux and in polarization profiles were close. Detailed properties of oscillations at different frequencies were analyzed on the example of two type IV bursts. One of them was observed on April 7, 2011 when a CME happened. Another one (August 1, 2011) was registered without any CME. The 7 April type IV burst had two periods in the frames 75-85 and 35-85 minutes. Interesting feature of these oscillations is decreasing periods with time. The observed decreasing rates dP/dt equaled 0.03-0.07. Concerning type IV burst observed on August 1, 2011 the period of its oscillations increases from 17 min. at 30 MHz to 44 min. at 10 MHz. Connection of type IV burst oscillations with oscillations of magnetic arches and CMEs at corresponding altitudes are discussed. The work is fulfilled in the frame of FP7 project "SOLSPANET".
In the present paper an analysis of the polarization properties of the solar decameter spikes is ... more In the present paper an analysis of the polarization properties of the solar decameter spikes is performed. We found that decameter spikes can possess both left and right circular polarization which changes from 0 up to 100% with an average value 50%.status: publishe
Purpose: A historical review of the experimental baselopment of low-frequency radio astronomy in ... more Purpose: A historical review of the experimental baselopment of low-frequency radio astronomy in Ukraine, its foundation half a century ago by an outstanding scientist S.Ya. Braude to the current state. Design/methodology/approach: The constant progress of electronic, computer and digital technologies, information and telecommunication technologies, theory and practice of antenna and receiving systems design, which introduction enriched the hardware and methodological ideology of construction and usage of the UTR-2, URAN, and GURT radio telescopes, have been used. Findings: The worldwide most effective national experimental radio astronomy means, the UTR-2, URAN, and GURT decameter-meter wave radiotelescopes, have been created and improved. The best combination of the systems main parameters: sensitivity; frequency band; spatial, frequency and temporal resolutions; noise immunity; uniformity of amplitude-frequency and space-frequency characteristics and multifunctionality has been p...
ABSTRACT Results of study of the continuum radio emission of the Sun in the decameter range are p... more ABSTRACT Results of study of the continuum radio emission of the Sun in the decameter range are presented. Observations were carried out with radio telescope URAN-2 in summer months in 2008-2009. Radio fluxes at frequencies 20 MHz and 25 MHz in frequency band 250 kHz were obtained during the time, when there were no active regions on the solar disk. Their average values for two years were 670 Jy and 850 Jy at frequencies 20 MHz and 25 MHz correspondingly. These fluxes are in agreement with high frequency values.
Two CME's (coronal mass ejections)were registered by SOHO and STEREO on April 2, 2011. The re... more Two CME's (coronal mass ejections)were registered by SOHO and STEREO on April 2, 2011. The results of observations, obtained by radio telescope URAN-2 of different CME manifestations in radio emission at the decameter wavelengths are discussed in the present paper. Particularly, it is reported about registration of a new type of fine structure of type II bursts.
This paper describes digital radio astronomical receivers used for decameter and meter wavelength... more 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.
Cutting edge astrophysical studies require more and more observing time at low-frequency radio te... more Cutting edge astrophysical studies require more and more observing time at low-frequency radio telescopes, which is limited and quite expensive. Modern digital signal processing systems still unable to provide affordable computational and storage resources to allow simultaneous beamforming in a wide frequency range for multiple studies. Low-frequency radio telescopes of a new generation are very flexible and could be split into subarrays or groups of subarrays for some studies which do not require large antenna effective area and high directivity. In this paper we make a survey of astrophysical studies in the frequency range 8–80 MHz using a rather small part of the low-frequency radio telescope GURT - the subarray of 25 active antennas.
Рассмотрены характеристики всплеска II типа с “елочной” структурой, который наблюдался 7 июня 201... more Рассмотрены характеристики всплеска II типа с “елочной” структурой, который наблюдался 7 июня 2011 г. в полосе частот 3÷33 МГц как наземными радиотелескопами (УТР-2, УРАН-2), так и космическими аппаратами (“СТЕРЕО”). Впервые в декаметровом диапазоне проведен статистический анализ основных параметров субвсплесков “елочной” структуры всплеска II типа (длительности и модуля скорости частотного дрейфа) отдельно для субвсплесков с положительным и отрицательным частотным дрейфом. Впервые также в этом диапазоне выполнена оценка степе- ни круговой поляризации тонкой структуры всплеска II типа. Обнаружена тонкая частотная структура “елочных” субвсплесков, которая по параметрам оказалась близкой к “бахроме”, наблюдающейся у солнечных S-всплесков. По характерному волнообразному изменению частоты “ствола” всплеска определены параметры корональных стри- меров, пересекаемых фронтом ударной волны. По данным наблюдений космических аппаратов “СТЕРЕО” и “СОХО” найдены направление и скорость распростр...
From 25 June till 12 August 2011 sporadic solar radio emission was observed simultaneously by thr... more From 25 June till 12 August 2011 sporadic solar radio emission was observed simultaneously by three separate radio telescopes: UTR-2 (Kharkov, Ukraine), URAN-2 (Poltava, Ukraine) and NDA (Nancay, France). During these observations several type II bursts with double and triple harmonics were registered, as well as type II bursts with complex herringbone structure. The events of particular interest were type II bursts registered on 9 and 11 August 2011. These bursts had opposite sign of circular polarization at different parts of their dynamic spectra. In our opinion we registered the emissions, which came from the different parts of the shock propagating through the solar corona. We have observed also groups of type III bursts merged into one burst, type III bursts with triple harmonics and type III bursts with "split" polarization. In addition some unusual solar bursts were registered: storms of strange narrow-band (up to 500kHz) bursts with high polarization degree (about...
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