In recent years, the INTERMAGNET geomagnetic observatory Argentine Islands of Ukrainian Antarctic Akademik Vernadsky station, located at Galindez Island, has been modernized. New devices were installed at the observatory: reference three-component fluxgate magnetometer LEMI-025, one-component Mag-01H Fluxgate Declinometer/Inclinometer with non-magnetic Wild T1 Theodolite (DI-magnetometer), and scalar Overhauser magnetometers GSM-19 and GSM-90. These devices have a high resolution and can carry out measurements with greater accuracy. Also, new methods of absolute observations and variation processing were introduced. In 2022, a new DI-magnetometer was installed; it practically did not change the baseline values of the variometer LEMI-025 compared to previous years, which indicates the reliability of the results, but made observations much more convenient. We present the results of processing absolute observations, carried out by different methods. Different techniques of calculating these observations are described, and certain shortcomings or inaccuracies in their application are noted. Recommendations to eliminate the identified shortcomings are proposed. The results of processing of absolute observations by different techniques are compared and the reason for the inconsistency of certain values is found. A new method of calculation of absolute observations is proposed, which was used at the observatory, which showed quite good results. In the new methodology, the calculation of errors of the DI-magnetometer, namely: the zero offset of the magnetic sensor, the azimuth collimation error δ and the elevation collimation error ε of its sensitivity axis relative to the axes of theodolite, is initiated. Analysis of these errors allows identifying and sometimes correcting the errors in absolute measurements. The installation of new devices and the application of new calculation methods made it possible to ensure better data quality and convenience of measurements at the station, to automate the data processing, preparation, and minimizing the influence of the human factor.

We fabricated arrays of parallel nanowires. Each of the nanowires consists of two different magnetic metals. Using Raman spectrometry, we studied the spectra that appear when a heterojunction between metals is illuminated by a laser and studied the effect of an external magnetic field on the spectra. We also measured the dependence of the intensity of the spectra on the position of the laser spot (in the region of heterojunctions) and on the radiation intensity and we hypothesized the threshold nature of excitation. Near the contact of two metals, the symmetry of the crystal lattice is broken due to amorphization, and a nonzero orbital momentum of the electrons appears. As a result, another radiative transition of electrons become allowed without spin flip, which is sensitive to the magnetic field.

The analytical theory is presented that describes the propagation of power lines emission (PLE) with frequency of 50/60 Hz in the heights range from the Earth surface to the magnetosphere. Validation of the theory is made by the comparison with earlier published results of numerical modeling. It is shown that the actual source of emission is a magnetic dipole formed by the power line current and by the secondary image current in the ground. The emission is propagating to the lower boundary of ionosphere, where its main part is reflected back, but some of the energy (a few percent) penetrates into the ionosphere. There it is transformed into a quasi‐flat whistler wave. The generation of current in ground and the reflection from the ionosphere are the main factors that reduce the emission into space. In the ionosphere wave fronts propagate approximately vertically, and the energy propagates in a certain direction that depends on the geomagnetic field inclination. Thus, the ionosphere acts as a focusing system that collects PLE into a unidirectional beam. The PLE intensity does not change with altitude within the total range of ionospheric heights. In the magnetosphere PLE is transformed to both magnetosonic and Alfvén waves and the emission splits into two rays: one propagates along the wave vector and the other one—along the geomagnetic field lines. A set of analytical solutions is presented allowing determining the change in PLE parameters with altitude depending on the source parameters and ionospheric conditions.

Ionosat-Micro is a fundamental scientific project devoted to the study of near-Earth space. The project is conceived as an answer to the challenges posed by the modern development of knowledge about Space Weather and the ionospheric responses to surface energy sources (such as weather phenomena, power lines operation, earthquakes and processes of their preparation, powerful technogenic hazards, etc.). Furthermore, the project Ionosat-Micro is a logical continuation and addition to previous ionospheric missions, such as Dynamics Explorer 2 (launched in 1982), Freja (1992), DEMETER (2004), Swarm (2013), and CSES (2018). The project is being prepared with the support and within the framework of The National Space Program of Ukraine and The Program of the National Academy of Sciences of Ukraine for Scientific Space Research. The article outlines the scientific principles of the project, describes the parameters of the space system being created, and the composition and operation logic of the scientific equipment. The project is to be implemented on board the satellite platform Microsat-M, which has been designed by Yuzhnoye State Design Office to conduct scientific and technological experiments. The planned satellite orbit is circular sun-synchronous with an inclination of 98 degrees and altitude of 600–700 km (orbital parameters, method and date of the launch are being clarified). Ionosat-Micro payload includes a set of scientific instruments designed to register the global structure and physical parameters of the neutral atmosphere and plasma, the structure and parameters of the space current systems and geomagnetic field, as well as the spectra and wave-forms of ULF-ELF-VLF electromagnetic perturbations. The Center for Collection, Processing, and Distribution of Measurement Data was created for the purpose of accumulating and targeted data processing.

The operation of flux-gate magnetometers (FGMs) onboard moving carriers faces several difficulties that limit their application in geophysics. Specifically, when FGM is used onboard UAV (such as drone) it has essential space rotation. As we show in the paper, it may create interference up to the value overcoming the useful signal. We show that the obstacles limiting the FGM sensitivity threshold are the FGM axes non-orthogonality and its sensors transformation factor non-uniformity. A possible solution of this problem is proposed: not to try to make these values as small as possible, but to determine them after production at thorough calibration and then use them at data processing. A new method to determine the real FGM channels mutual orthogonality deflection and transformation factors non-identity with given precision is described and experimentally confirmed.

The program and results of physical research in the international (5 countries) space experiment «The situation (1 stage)», conducted onboard the Russian segment of the International Space Station (ISS) in the period 27.02.2013 to 09.05.2015, is presented. The methods and scientific tasks of the experiment and the composition of the Plasma-wave complex based on the combined wave diagnostics method are described in detail, and designed to conduct geophysical studies through long-term monitoring measurements of the electromagnetic parameters of the ionosphere plasma and plasma-wave processes associated with the manifestation in the ionosphere of the solar-magnetosphere-ionosphere and ionosphere-atmosphere relationships, i. e., parameters of space weather. Studies in the near-surface zone of plasma-wave processes of interaction of an extra-large spacecraft, like ISS, with the ionosphere are necessary for both applied and fundamental geophysical studies. The electric and magnetic fields and currents measured at the surface of the ISS are determined by the parameters of the surrounding ionosphere plasma and the nature of the interaction of the materials on the surface with this medium. Key words: orbital space station, fundamental space research, ionosphere plasma, plasma-wave processes, electromagnetic fields and radiation, scientific instrument, space weather.

Aquifers are usually characterized by low electrical resistivity due to conductive fluid presence in the interconnected pores. In geothermal regions this resistivity is still lower because the ions of dissolved minerals in the hot water possess higher mobility which increases the conductivity of solution. All inductive electromagnetic (EM) methods of geophysics reliably resolve highly conductive bodies or layers in the subsurface. Among other, the magnetotelluric (MT) one has several advantages. The most important one is that it is basically non destructive for environment, since it utilize the natural geomagnetic field variations as a source. MT allows recording of the EM field variations in a wide frequency (periods) band what directly relates to different depth of exploration. To this, with recent progress in instrumentation parameters and modern approaches development to data processing and interpretation the application of MT method became very useful and cost efficient for geothermal study. It has to be stressed that the successful application of MT method greatly depends on the used instrumentation parameters. The wide band MT station (audio MT or AMT) may be considered as the most suitable instrument for the geothermal research. The frequency band from 0.001 to 10000 s allow us to study the subsurface conductivity distribution from a few hundred (sometimes even from a few tens) of meters to tens of kilometers. The most important parameters of corresponding MT instruments, their recent upgrade in modern wide band AMT instruments are presented and compared. It is necessary also to mention that increasing data processing quality postulates, following from the recent practice of the MT results, the application of remote reference technique with simultaneous using as a minimum of two synchronously operating MT instruments. The details of such processing procedures with corresponding examples are discussed in our report also.

Assessment of a power lines condition is an important task for all countries. It includes GPS mapping of the: 1) wire breaks; 2) places of the increased current leakage, for example corona detection; 3) degree of wires sagging between power line towers; 4) location and conditions of the power line towers; 5) vegetation encroachment along a power line corridor. Considering that power line currents, including leakage currents, create strong magnetic field, use of magnetometers in the range from DC to sound frequencies for the solution of tasks 1-4 is highly prospective. At the same time, it is possible the control of the vegetation critical proximity to a power line adjacent zone by the increased leakage current (threats of the increased leakage current or breakdown to a tree crown). Thus the task 5 also can be solved. The goal of the present report is to introduce the new design of miniature low-weight three-component sensor for measurement of alternative vector magnetic field onboard UAV – induction magnetometer (IM) - with autonomous system including two-component tiltmeter and GPS antenna inside in order to obtain precise measurement timing, UAV coordinates and altitude during movement. These data are stored in the SD memory card. Construction details, tests results and technical specifications of this IM for are presented.

The purpose of this article is to attract the attention of the scientific community to atmospheric gravity waves (GWs) as the most likely mechanism for the transfer of energy from the surface layers of the atmosphere to space heights and describe the channel of seismic-ionospheric relations formed in this way. The article begins with a description and critical comparison of several basic mechanisms of action on the ionosphere from below: the propagation of electromagnetic radiation; the closure of the atmospheric currents through the ionosphere; the penetration of waves throughout the neutral atmosphere. A further part of the article is devoted to the analysis of theoretical and experimental information relating to the actual GWs. Simple analytical expressions are written that allow one to calculate the parameters of GWs in specific experimental situations. Specificity of GW dispersion properties and features of their propagation are analyzed on this mathematical basis, processes of amplitude amplification and dissipation of GWs with height are investigated, the mechanism of generation of ionosphere-magnetosphere current systems is described and their quantitative characteristics are determined. The experimental part presents an analysis of GWs global distribution in the thermosphere derived from the data of the instrument NACS (Neutral Atmosphere Composition Spectrometer) onboard the satellite DE-2 (NASA, 1981-1983). The statistical association of registered ionospheric disturbances with earthquakes is demonstrated. The results of DE-2 data processing are backed up by comparison with data from the DEMETER satellite (CNES, 2005-2010) whose purpose was to study the ionospheric effects of earthquakes. Specific features of GWs that characterize these waves as a factor of influence on the ionosphere from below are indicated.

We present a comparison of several basic mechanisms of influence on the ionosphere from below discussed in the literature: the propagation of low-frequency electromagnetic radiation; the short circuits of electric currents through the ionosphere; the penetration of neutral atmosphere waves. It is shown that atmospheric gravity waves (GW) are the most likely candidate for the role of a carrier of seismic-ionospheric interaction, which allows one to explain (i) the transport of significant energy fluxes into the ionosphere, (ii) the weak dependence of the intensity of ionospheric disturbance on the magnitude of the earthquake, (iii) the shift of ionospheric disturbances per thousand kilometers horizontally relative to the earthquake; (iv) and the generation of an ionospheric electromagnetic response. A detailed review of the theoretical and experimental data on GW is given. Simple analytical expressions are written that allow one to calculate the parameters of GW in specific experimental situations. The processes of amplitude amplification and dissipation of GW with height are investigated, the mechanism of generation of electromagnetic perturbations when GW passes the dynamo-layer is described, and the quantitative characteristics of perturbations are determined. The experimental part of the work presents the study of GW global distribution at ionospheric heights according to DE-2 satellite data and statistical analysis of GW relations with earthquakes. The results of the DE-2 are backed up by comparison with the published data from the DEMETER mission.

The article describes the main features of upgrading the magnetometric complex based on the LEMI-025 variometer in January-April 2019 at the geomagnetic observatory (code AIA) of the Ukrainian Antarctic Akademik Vernadsky station. The observatory’s old magnetometric complex consisted of two LEMI-008 (No. 02 and No. 16) variometers and one POS-1 scalar magnetometer. The measurements of LEMI-008 and POS-1 were not mutually synchronized and this was one of the main problem. Every measuring instrument taken individually as a component of the whole magnetometric complex had good individual properties. However, in general, the complex as an entire system had reduced performance, mainly due to the lack of mutual synchronization of measurements. Some preliminary test results are also presented. Main objective. One of the main task of upgrading the AIA observatory was to install a new variometer that is compatible with the requirements of the 1-second INTERMAGNET data standard. For two decades, old LEMI-008 variometers at Akademik Vernadsky station have shown high baseline stability, which meets INTERMAGNET requirements. Unfortunately, the noise characteristics of old variometers, the accuracy of synchronization with UTC, and the resolution do not longer meet the current INTERMAGNET requirements for devices that produce 1-second data. Measurements of LEMI-008 variometers and POS-1 scalar magnetometer were not mutually synchronized. Due to lack of reliable mutual synchronization, the differences between the field vector modules, calculated indirectly from the variometer measurements and measured directly with the scalar magnetometer, varied and could be unreliable. With strong geomagnetic disturbances, this reduced the overall accuracy of the magnetometric complex as an integral measuring system, although the complex consisted of high-precision instruments. Only one of LEMI-008 variometers was equipped with GPS synchronization. This made data processing difficult. Therefore, one of the crucial upgrading tasks was creation of a system for mutual synchronization of measurements provided by the variometer LEMI-025 and the scalar magnetometer POS-1 with an accuracy of approximately 0.1 s (but not worse than 1 s) using control computer. Methods. The problem of mutual synchronization of the measurements of the LEMI-025 variometer and the POS-1 scalar magnetometer (at the stage of upgrading the magnetometric complex as a whole system) was solved using a control computer by periodical adjusting the POS-1 clock and starting its measurement cycles with a given timing advance. New data arrays were obtained while the LEMI-025 magnetometer was operated in test mode. Using the Bartlett’s method and spectral harmonics averaging, the noise level of the magnetometers during a geomagnetically quiet day was estimated. The results of absolute measurements of the geomagnetic field components, regularly carried out in the observatory by two methods, were analyzed and the baselines values of the LEMI-025 magnetometer were estimated. The comparative analysis of the records of the Earth magnetic field intensity, obtained by direct measurements with a scalar magnetometer POS-1 and calculated from the baseline-adjusted components of the LEMI-025 variometer, was performed. Using the obtained baseline values and the total field difference signals the high calibration accuracy of the new variometer was confirmed and the orientation errors of its sensitivity axes in the geographical coordinate frame were estimated. Conclusions. Our preliminary results confirm that the characteristics of new LEMI-025 variometer meet the INTERMAGNET requirements. The orientation errors of LEMI-025 sensor do not exceed 5 arc minutes. The base line is quite stable. All its components have dispersion within ±2 nT, without pronounced temporal drift. The test results of LEMI-025 variometer showed that the characteristics of all magnetometric instruments in the measuring pavilion of the AIA observatory should be mutually agreed in terms of electromagnetic compatibility.

Electromagnetic compatibility (EMC) is an important requirement for spacecrafts due to the limitation of their volume and the possibilities of the layout of individual subsystems. Interference from satellite service systems are the main problem in conducting high-sensitivity measurements of magnetic fields when studying wave processes in plasma in the range of low frequencies. This is especially true for the becoming recently popular very small satellites - CubeSats (CS) with sensitive equipment for measuring electric and magnetic fields in the range from direct current to low frequencies. In order to minimize the mutual influence of the payload and service systems, it is necessary to determine the frequency and amplitude of the main spectral components of the emitted magnetic field of each satellite subsystem to reduce the level of the interference or, if not possible, to take into account when processing data. A special measuring system, created for registration and estimation of magnetic interference in the ULF range, is described in the article. This system consists of two identical three-component induction magnetometers, data acquisition unit, power supply unit, and control computer with a corresponding set of programs. With this system, the level of the AC magnetic field, generated by each of the subsystems of the CS, was measured and digital processing was performed. For the separation of the studied and background signals, data obtained from two identical three-component induction magnetometers of the system were used with the following solution of the inverse problem the determination of the parameters of the radiation source using the measured magnetic field generated by this source at two points. The results of the EMC tests for the CS developed under the SEAM project, the values and locations of the equivalent magnetic dipoles of the radiation of the separate subsystems, which are the sources of radiation in the CS, are given.

Abstract. The experiments on-board Vernov satellite were aimed on the study of high energy (relativistic and sub-relativistic) electron acceleration and losses in the trapped radiation areas as well as high altitude electric discharges in the upper Atmosphere. A separate task was study electromagnetic-wave phenomena in the near Earth space and the upper Atmosphere. During observations on 10 December 2014 interesting phenomena were discovered. They are connected to non-linear effects in wave activity of the type of two or three wave decays as well as splitting into two wave structures. Whistlers with specific unusual temporal structure of swallowtail type were observed on the spectral diagrams (sonograms), which were obtained for this time. It was shown that such signals can be caused by seismic activity. The signals of the type of whistler with long tail were also observed. Such signals were also detected by ground stations.

Extraterrestrial gamma-ray astronomy is now a source of new knowledge in the fields of astrophysics, cosmic-ray physics, and the nature of dark matter. The next absolutely necessary step in the development of extraterrestrial high-energy gamma-ray astronomy is the improvement of the physical and technical characteristics of gamma-ray telescopes, especially the angular and energy resolutions. Such a new generation telescope will be GAMMA-400. GAMMA-400, currently developing gamma-ray telescope, together with X-ray telescope will precisely and detailed observe in the energy range of ~20 MeV to ~1000 GeV and 3-30 keV the Galactic plane, especially, Galactic Center, Fermi Bubbles, Crab, Cygnus, etc. The GAMMA- 400 will operate in the highly elliptic orbit continuously for a long time with the unprecedented angular (~0.01{\deg} at E{\gamma} = 100 GeV) and energy (~1% at E{\gamma} = 100 GeV) resolutions better than the Fermi-LAT, as well as ground gamma-ray telescopes, by a factor of 5-10. GAMMA-400 will permit to resolve gamma rays from annihilation or decay of dark matter particles, identify many discrete sources (many of which are variable), to clarify the structure of extended sources, to specify the data on the diffuse emission.

Fermi-LAT has made a significant contribution to the study of high-energy gamma-ray diffuse emission and the observations of 3000 discrete sources. However, one third of all gamma-ray sources (both galactic and extragalactic) are unidentified, the data on the diffuse gamma-ray emission should be clarified, and signatures of dark matter particles in the high-energy gamma-ray range are not observed up to now. GAMMA-400, the currently developing gamma-ray telescope, will have angular (∼0.01∘ at 100 GeV) and energy (∼1% at 100 GeV) resolutions in the energy range of 10–1000 GeV which are better than Fermi-LAT (as well as ground gamma-ray telescopes) by a factor of 5–10. It will observe some regions of the Universe (such as the Galactic Center, Fermi Bubbles, Crab, Cygnus, etc.) in a highly elliptic orbit (without shading the telescope by the Earth) continuously for a long time. It will allow us to identify many discrete sources, to clarify the structure of extended sources, to specify the data on the diffuse emission, and to resolve gamma rays from dark matter particles.

The copters are the recent challenge and many instruments are attempted to be used with them, including magnetometers. The last is a pending problem, especially for component magnetometers, because of the complexity of reducing the data obtained in permanently rotating frame system to the data in geomagnetic frame system. Next problem is high interference level due to copterelectrical circuits and its moving metal parts during magnetometer operation. A possible approach to the first problem solution is presented.

The GAMMA-400 gamma-ray telescope with excellent angular and energy resolutions is designed to search for signatures of dark matter in the fluxes of gamma-ray emission and electrons + positrons. Precision investigations of gamma-ray emission from Galactic Center, Crab, Vela, Cygnus, Geminga, and other regions will be performed, as well as diffuse gamma-ray emission, along with measurements of high-energy electron + positron and nuclei fluxes. Furthermore, it will study gamma-ray bursts and gamma-ray emission from the Sun during periods of solar activity. The energy range of GAMMA-400 is expected to be from ~20 MeV up to TeV energies for gamma rays, up to 20 TeV for electrons + positrons, and up to 10E15 eV for cosmic-ray nuclei. For high-energy gamma rays with energy from 10 to 100 GeV, the GAMMA-400 angular resolution improves from 0.1{\deg} to ~0.01{\deg} and energy resolution from 3% to ~1%; the proton rejection factor is ~5x10E5. GAMMA-400 will be installed onboard the Russian space observatory.