About Research Programs at the Radio Telescope "Uran-4" Ira Nasu – Monitoring of Fluxes of Powerful Radio Sources, Study of the Sun's Supercorona, Observations of Solar Eclipse

Abstract

During 2020–2023, an initiative series of observation programs was carried out on a radiometer designed and manufactured by V.V. Galanin. Among them are observations of ionospheric scintillations of powerful radio sources Cas A, Cyg A, Vir A, Tau A, Per A, on the URAN-4 radio telescope (IRA NASU) at frequencies of 20 and 25 MHz. The observations were carried out at various states of Solar and geomagnetic activity and allow us to analyze the response of the ionosphere in the region of the Odessa Magnetic Anomaly to disturbing events. It was found that the radio source 3C 84 (Per A) is the least noisy at the location of the URAN-4 antenna and is well suited for studying the ionospheric response during magnetic storms. The recorded scintillation periods of the studied radio sources, on "calm" days, are in the range of 1-2 minutes. During magnetic storms, the periods of scintillations are reduced to 10-30 seconds. The paper considers the features of the response of scintillations of different radio sources to a magnetic storm, since they shine through different spatial regions of the ionosphere. Of particular interest are observations of the radio source Tau A (3C 144), which annually, in June, shines through the Solar Supercorona. Processing scans of such observations of the 3C 144 source shows an increase flux variations with an average "period" of about 5-10 seconds. Observations were also made to record the features of radio background variations during partial Solar eclipse. It is shown that during a Solar eclipse, the level of background radio noise increases significantly. At the same time, the background level on the next day after the eclipse was still quite high. A more detailed analysis of this effect is planned and, if possible, repeated observations.