Abstract. Flux density variations of the extragalactic radio source OJ 287 are studied by applying the wavelet and the singular spectrum methods to the long-term monitoring data at 14.5, 8.0 and 4.8 GHz acquired at the University of Michigan Radio Astronomy Observatory during 40 years. This monitoring significantly supplements the episodic VLBI data. The wavelet analysis at all three frequencies revealed the presence of quasiperiods within the intervals 6.0-7.4 and 1.2-1.8 years. The singular spectrum analysis revealed the presence of quasiperiods within the intervals 6-10 and 1.6-4.0 years. For each quasiperiod the time interval of its existence was determined.
ABSTRACT. We investigated the data of monitoring of flux density of extragalactic sources 3С446 and 3C345, which was held on 26-meter radio telescope of University of Michigan at frequencies 14.5, 8 and 4.8 GHz. The data of observations were investigated using singular spectrum analysis and wavelet-analysis. According to the results of wavelet analysis for each year of observations, graphics of "spectra periods" were built to determine the contribution of individual periods in the activity of the radio source. The results obtained with two different methods showed a good correlation between them. For a long time component of the flux the periods of ~ 5 -9 years were found. For short term components the periods of ~ 1 -4 years are presented. The results obtained using two different methods were compared with VLBI radio maps, which were obtained by the program MOJAVE. The changes of periods over time are associated with certain physical processes in the system "core -accretion disk -jet" and with appearing of new bright components (knots) in the jet.
Abstract.We investigated the monitoring data of extragalactic sources 3C120 and BL Lac. This monitoring was held with University of Michigan 26-meter radio telescope. To study flux density of extragalactic sources 3C120 and BL Lac at frequencies of 14.5, 8 and 4.8 GHz, the wavelet analysis and singular spectrum analysis were used. Calculating the integral wavelet spectra revealed long-term components (11 -4 years) and short-term components (3.4 -0.7 years) in 3C120. BL Lac has long-period components of 7 -8 years and short-term components of 1 -4 years. Studying of VLBI radio maps (by the program Mojave) allowed investigating features of components movement relatively to the VLBI core. The data of radio astronomy observations were also investigated using singular spectrum analysis. This method does not use the analyzing function, so its calculations allow to distinguish various components of investigated series with a high accuracy. To get spectral power distribution depending on time in the studied narrowband components obtained by singular spectrum analysis, short-term Fourier transformation was used.
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