Перегляд за Автор "Kravetz, R. O."

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  • Ескіз
    Документ
    Connection between the cme velocities and decameter radio bursts parameters from URAN-4 observations
    (Одеський національний університет імені І. І. Мечникова, 2015) Halanin, V. V.; Isaeva, E. A.; Kravetz, R. O.
    The paper reports the results of the research of connection between the coronal mass ejections (CME) with the IV type continual decameter bursts parameters. As the parameters characterizing the CME velocity, we used the integrated flux of the radio bursts and background intensity on 20 and 25 MHz frequencies. The analysis demonstrated that the connection between the CME velocity and IV type bursts increases, if we take into account the intensity of the radio bursts and background on two polarizations at a given frequency. In this case, the correlation coefficient is ≈ 0.75.
  • Ескіз
    Документ
    Evaluation of coronal shock wave velocities from the ii type radio bursts parameters
    (Одеський національний університет імені І. І. Мечникова, 2015) Halanin, V. V.; Isaeva, E. A.; Kravetz, R. O.
    The work presents the results of research of connection between the coronal shock waves and the parameters of type II (mII) meter-decameter bursts in 25- 180 MHz band for 66 solar proton events. The velocities of coronal shock waves for this two cases where determined. In the first case the velocities of the shock waves was evaluated according to the Newkirck model and in the second case – directly from the type II radio burst parameters. The calculated values of shock waves velocity was compared with the same velocity values that is published on NGDC site. The comparative analysis showed that precision of coronal shock waves velocity estimation which gets directly from type II radio bursts parameters was higher than the same one which used the Newkirck model. Research showed that there is exist the sufficiently strong connection between the shock wave velocity and the delay of type II burst intensity maximum on the second harmonica. Correlation coefficient between the studied parameters was equal to ≈ 0.65.
  • Ескіз
    Документ
    Radio telescope Uran-4 and the problem of radio interference
    (Одеський національний університет імені І. І. Мечникова, 2018) Galanin, V. V.; Lytvynenko, O. A.; Derevyagin, V. G.; Kravetz, R. O.
    The URAN-4 decameter radio telescope, which is located in the village of Mayaki of the Odessa region, is an element of system of the URAN radio telescopes (Ukrainian Radiointerferometer of the Academy of Sciences). The radio telescope is used according to the following scientific programs: measurements in the composition of the Interferometer with the Super Large Base (VLBI), to study the angular structure of discrete radio sources; the study of the nonstationarity of the flux of cosmic radio sources and the study of the influence of the space environment on the characteristics of the received signals. RT URAN-4 operates at frequencies of 10-30 MHz and consists of an antenna and an equipment complex. A telescope antenna is an electrically controlled phased array of 128 turnstile vibrators. It identifies two linear signal components and is endowed with the possibility of changing the position of the antenna pattern in space (2048 discrete positions of the beam). The geometric dimensions of the array 238 meters (West-East direction) and 28 meters (North-South direction). The size of the antenna pattern in the modulation mode of signal reception at a frequency of 25 MHz is 2.7 x 22 degrees. In the VLBI interferometer mode, a resolution of about 2 seconds of arc is realized. The instrumental complex of the RT URAN-4 is represented by two types of modulation radiometers, which make it possible to measure the flux densities of radio sources and apparatus intended for VLBB measurements. The working frequency range in which RT URAN-4 operates has a high level of radio interference. The work gives definitions of interference acting in the decameter range. Considered methods of dealing with them. One of the methods to combat interference is the work of the radio telescope on the frequencies permitted and legally protected from interference, the list of which is given in the article. The paper deals with issues related to the organization of the security zone around the radio telescope. On its territory, the maximum allowable power for existing nearby transmitting radio facilities and interfering industrial facilities should be legitimized, in the designated working lanes. At the same time, a monitoring service for the radio spectrum should be organized. The paper deals with the developed and manufactured portable direction finder. Its characteristics are given, recommendations on its use are given.