Space-Weather Phenomena Observed in Experiments on CubeSats of the MSU Sozwezdie-270 during the 2024 Heliogeophysical Disturbances

Deployment of the Moscow State University (MSU) nanosatellite constellation “Sozwezdie‑270” is continuing. To date, 20 CubeSat satellites have been launched with equipment for monitoring cosmic radiation and electromagnetic transients of various natures, including atmospheric, astrophysical and solar origin. This paper uses data from five CubeSats launched on June 27, 2023 (Avion, Monitor-2, Monitor-3, Monitor-4, UTMN-2), and two CubeSats launched on November 5, 2024 (Altair, ArcticSat). Each of them is equipped with DeCoR scintillation detectors for recording hard X-ray and γ radiation and charged particles specially developed at the Skobeltsyn Institute of Nuclear Physics, MSU, for such experiments. The paper presents the results of observations of space-weather phenomena that lead to significant changes in radiation conditions in near-Earth space. Such phenomena that can be recorded in experiments on the CubeSats of the “Sozwezdie‑270” group include hard X-ray radiation (HXR) and γ radiation from solar flares, solar cosmic rays (SCR) recorded on CubeSats in the polar-cap region, and variations in the intensity and spatial structure of the distribution of high-energy electron fluxes in the Earth’s outer radiation belt during magnetic storms caused by changes in solar wind parameters due to active processes on the Sun—both the arrival of coronal mass ejections in the Earth’s orbit and high-speed solar-wind flows from coronal holes. The table of solar flares observed in HXR on the MSU CubeSats from September 2023 to February 2025 is given.