Vol 57, No 1 (2019)

Spectral polarization observations of radio sources above sunspots are regularly carried out with the RATAN-600 radio telescope (RATAN is a Russian acronym for the Radio Astronomical Telescope of the Academy of Sciences). The in-depth studies of the spectra reveal new effects. In this paper, we analyze the manifestation of radio emission of the fourth gyrofrequency harmonic in microwave spectra obtained with 1-percent frequency resolution in a range of 3–18 GHz. Registration of the extraordinary mode in the short-wavelength range of the spectrum is compared to the model calculations of the second-to-fifth gyrofrequency harmonics against a background of the thermal bremsstrahlung emission of flocculi, surrounding the spot structure of an active region. The brightening of the extraordinary mode in the short-wavelength spectral range and the kinks in the intensity spectra of emission are analyzed. The interpretation of the RATAN-600 observational data with probable diagnostics of the emission of the fourth gyrofrequency harmonic is considered as examples.

According to the data of ground-based measurements of cosmic rays (CRs) from the world network of stations, the behavior of CR intensity during the geomagnetic disturbance in January 2015 has been studied using the spectrographic global survey method. The spectra of CR variations and spectrum indexes of these variations are presented, when approximating the spectrum by the power function of the particle rigidity in the rigidity range from 10 to 50 GV, as well as pitch-angular anisotropy of CRs. It is shown that the spectrum indexes of CR variations at its approximation by the power function of the particle rigidity in the phase of maximum modulation are greater than in the phases of decay and recovery of CR intensity.

Analysis of the properties of the winter anomaly in E layer critical frequency foE in the nighttime (22.00–02.00 LT) polar ionosphere is performed based on data of the Tromso digital ionospheric station during 1995–1998. It is found that for these conditions, the winter anomaly in foE, i.e., the excess of the winter values of foE over summer values is typical not only for the median, but for the values of foE averaged over a month as well. The amplitude of the winter anomaly in foE is minimal for quiet geomagnetic conditions and reaches a maximum under moderate and enhanced geomagnetic activity (Kp = 3–4), mainly due to stronger increase in foE with geomagnetic activity increase in winter. This property of the winter anomaly is qualitatively and even quantitatively similar to the property of winter–summer asymmetry in fluxes of accelerated electrons to which discrete aurorae are related. That is why foE data from ionospheric stations could serve as an indicator of such fluxes in the polar ionosphere.

In this paper, we present the results of comparison of the experimentally measured and calculated values of the absorbed radiation doses from galactic cosmic rays for several space missions to the Moon and Mars. Galactic cosmic ray (GCR) fluxes were calculated using SINP-2016 model. A brief description of the method for calculating fluxes and absorbed doses is given. It is shown that the calculated values of the absorbed dose are in satisfactory agreement with experimental data.

The Spectrum-Roentgen-Gamma (SRG) project is intended for surveying the entire sky in the X‑ray band using two telescopes mounted onboard the spacecraft of the same name (SRG). In addition, some specially chosen areas of the sky and some radiation sources are planned to be investigated after the completion of the survey. The spacecraft was planned to be launched in 2018 into the vicinity of solar-terrestrial collinear libration point L2, using the Proton-M launch vehicle with a DM-03 block upper stage. The technology for completely surveying the celestial sphere consists in scanning by rotating the parallel axes of telescopes around the spacecraft axis, which roughly followed the direction to the Sun. The measurement data, stored onboard the spacecraft, would then be transmitted to the ground receiving stations using the mean gain antenna, the axis of which coincided with the spacecraft’s axis of rotation. This imposed some constraints on the mission design. These constraints included the permissible amplitude of the trajectory of spacecraft motion relative to the libration point in the direction orthogonal to the Sun–Earth line. In addition, the consumption of the onboard propellant was allowed only for orbit correction needed for keeping the spacecraft near the libration point. In this connection, a method was developed using the upper stage in order to decrease the mentioned amplitude down to acceptable values, in the conditions of the requirements imposed on the unit. The paper presents an assessment of its effectiveness.