Study of variability of 3C 144 (Taurus A) radio source at frequencies 1.6, 5, 6.1 GHz with passage through the solar supercorona

The galactic radio source 3C 144 (identified with the Crab Nebula) is one of the most important objects for studying the structure of the solar wind. Being in ecliptic plane and approaching minimum distance to the Sun on June 15 every year, 3C 144 shines through the Solar supercorona, which is observed (usually at meter and decameter wavelengths) in the form of radio emission scintillations on inhomogeneities of the solar wind. This paper presents preliminary results of the study of variability of 3C 144 (in May, July 2019) at frequencies 1.6, 5, 6.1 GHz at the 32-m radio telescope of the Ventspils International Radio Astronomy Center in Latvia. A possible relationship between active events on the Sun, which caused disturbances in the solar wind and observed flux density variability, is shown. Characteristic times of variability, observed at 1.6 GHz, are from several hours to 20 minutes; at frequencies of 5 and 6.1 GHz, from 2-3 hours to 40-30 minutes. Also, fast variations of solar wind parameters (proton density, plasma pressure, wind speed, plasma temperature) were analyzed using satellite data from the NASA OmniWeb catalog, with hourly, five minute and one minute averaging. Using the method of continuous wavelet analysis, it was shown that quasiperiods in variations of 3C 144 flux density, in band from 10 to 3 hours and from 2 hours to 20 minutes, are close to corresponding quasi-periods in variations of the solar wind parameters. Additionally, variations of 3C 144 flux density were analyzed according to the monitoring program on the “URAN-4" radio telescope at the Odessa Observatory of the RI NASU (frequency 25 MHz, decameter wavelength range). Changes in flux of this radio source at decameter waves depend on the time of culmination. For day and evening observations, a response of its flux to the extreme appearance of solar and geomagnetic activity is noted. For night observations, changes in radio source flux correlate with solar wind parameters. Thus, combination studies of radio source 3C 144 in centimeter, decimeter and decameter wavelengths range complement each other. They make it possible to identify effects of the appearance of variability of the radio source itself, the in uence of inhomogeneities in solar wind and contribution of the ionosphere as a response to active events on the Sun.