## 1 Introduction  
A geomagnetic observatory is a complex facility that carries out precise measurements of the components of Earth's magnetic field on a regular basis. The creation of and support for such posts that carry out continuous measurements of the elements of Earth's magnetic field have long been relevant due to the constant need for geomagnetic data, which are used in numerous studies of fundamental and applied research in the Earth sciences and solar-terrestrial relations [1]. The installation of a geomagnetic observatory is a sequential multi-step task, which includes the selection of a suitable location, the study of the geomagnetic anomalies from geological or artificial near-surface sources [2], the determination of sites for the construction of a magnetic pavilion and the installation of an azimuth mark for absolute measurements, the selection of non-magnetic construction materials for pavilions, the design of communication and power supply networks, the selection of heating devices and temperature stabilization systems, and so on. During collaborations of scientific institutions on the deployment of geomagnetic observatories, several guidelines were developed [3, 4], and these provide fairly comprehensive coverage of the mentioned issues. However, they describe only general rules and recommendations for deploying magnetic observatories, and many comment factors always affect the installation progress of each individual observatory. In particular, the conditions of the location of an observatory are different in different environments. In regions with cold continental or polar climates, the proper temperature stabilization of vector fluxgatemagnetometers requires insulation of the pavilion walls and an automated heating system that compensates for seasonal temperature fluctuations, whereas, in mild climate conditions, such additional adaptations are less relevant. Another issue is the geological structure of the observatory site, the underlying rocks, and their magnetization, which contributes to lithospheric anomalies. Therefore, it is impossible to simply replicate observatories in different locations in exactly the same way. Every observatory is unique in this regard, and different observatories require different approaches for their proper functioning. Thus, research communities and teams engaged in the deployment of magnetic observatories are free to make independent choices and apply any technical solutions for proper equipment within the regulations and constraints listed in the guidelines. Nevertheless, at various construction stages, specific procedures and technical solutions are required, and these take local settings and instrumentation into account. For example, in the Geophysical Center of the Russian Academy of Sciences (GC RAS), a specific methodology was developed for geophysical studies with the aim of searching for suitable magnetic observatory locations by using modern GNSS technologies [2]. Next, some cheaper solutions were found for the heating and thermal stabilization of measurement pavilions [5], such as replacements for non-magnetic copper or ceramic heaters. Finally, in recent years, various non-magnetic composite materials that can be used in observatory pavilions have been introduced into construction practice. These new materials should be characterized from the magnetic point of view to ensure that they do not introduce magnetic anomalies. Measurements of the magnetic susceptibility of rocks that are conducted either in situ or in the laboratory provide information for various studies in the areas of geology, archaeology, technical geophysical tasks, etc. However, there have not been very many studies that have provided detailed descriptions and application examples in the framework of magnetic observatory construction and maintenance.