Abstract—We present new results of the study of ET Dra—a star of the FK Com type—based on observations carried out at the Zvenigorod Observatory of the Institute of Astronomy of RAS with the help of the FRAM-ORM telescope of the La Palma observatory (Spain) and the broadband optical monitoring system Mini-MegaTORTORA, located on the territory of the SAO RAS. We have studied changes in the shape of the light curve caused by the rotational modulation of a star with spots on its surface and the long-term variability of the star’s brightness. An independent determination of the rotation period of $${{P}_{{{\text{phot}}}}}$$ was carried out using all sets of observations available to us. The increase in the brightness of the star near HJD 2459044 during observations with the FRAM-ORM telescope in all three filters was interpreted by us as a stellar flare. Our flare energy estimates are $$2.8 \times {{10}^{{37}}}$$ , $$1.9 \times {{10}^{{37}}}$$ , and $$1.5 \times {{10}^{{37}}}$$ erg in the $$B$$ , $$V$$ , and $$R$$ wavelength ranges, respectively. Observations with a duration of more than 2200 days, carried out at the SAO RAS, opened up the possibility of analyzing the long-term brightness variability of ET Dra. Evidence was found for the existence of cycles lasting 580 days and 810 days (1.55 and 2.23 years, respectively).

Based on the available photometric data spanning almost 8000 days (21.9 years) of observations of a bright G5 V dwarf, solar-type star HD 4915, we carried out a study of the manifestations of its activity, probably transitioning to a state similar to the Maunder Minimum. To estimate the duration of the possible activity cycles of the star, we used three independent data sets. We obtained evidence of HD 4915 light variations, including the interval of time corresponding to a decrease in its chromospheric activity variations. Based on the constructed power spectrum, we can suggest the existence of possible cycles of the order of 1640 and 630 days (4.5 and 1.7 years) for the object’s brightness, which are comparable with the chromospheric activity cycle estimate of 4–4.2 years, significantly shorter than the duration of the magnetic activity cycle of the Sun, which is a distinguishing feature of HD 4915. Using photometric observations of the star from Kamogata Wide-field Survey, including data from the measurements taken after 2018, when it could have been starting an activity phase similar to the Maunder Minimum, we obtained indications of possible 450, 1260 and 2000 day cycles (1.23, 3.5 and 5.5 years) and made a conclusion about the presence of cyclic light variations during this supposed lower activity state of HD 4915. We discuss the probable estimate of the star’s rotation period. A consideration of the HD 4915 data available in the TESS archive for four observing sets led us to conclude that they are unsuitable for determining its rotation period.

9-канальная система Мини-МегаТОРТОРА (ММТ-9) позволяет исследовать метеоры с блеском вплоть до видимой звездной величины 10.5 m с временным разрешением 0.1 секунды. База данных содержит свыше 330 тысяч метеоров, зарегистрированных с 2014 по 2022 г. В базисных наблюдениях с ММТ-9 и широкоугольным телескопом FAVOR были зарегистрированы около сотни треков, для которых были получены траектории метеоров в атмосфере. Начаты спектральные наблюдения метеоров с помощью объективной призмы, которой снабжен один из каналов ММТ-9. В этом режиме будут изучаться спектры метеоров вплоть до 6 видимой звездной величины со спектральным разрешением 150 Å. The 9-channel Mini-MegaTORTORA (MMT-9) system makes it possible to study meteors with limiting apparent magnitude to 10.5 m with a time resolution of 0.1 seconds. The MMT-9 database contains over 330 thousand meteors registered from 2014 to 2022. In double-station observations with MMT-9 and the FAVOR wide-angle telescope, about a hundred meteor tracks were recorded, for which atmospheric trajectories were obtained. Spectral observations of meteors have begun with the help of an objective prism, which is equipped with one of the MMT-9 channels. In this mode, the spectra of meteors up to apparent magnitude 6 will be studied with a spectral resolution of 150 Å.

We describe the properties of Mini-MegaTORTORA (MMT-9) nine-channel wide-field optical sky monitoring system with subsecond temporal resolution. This instrument can observe sky areas as large as 900 deg2, perform photometry in three filters close to Johnson BV R system and polarimetry of selected objects or areas with 100–300 deg2 sizes. The limiting magnitude of the system is up to V = 11m for 0.1 s temporal resolution, and reaches V = 15m in minute-long exposures. The system is equipped with a powerful computing facility and dedicated software pipeline allowing it to perform automatic detection, real-time classification, and investigation of transient events of different nature located both in the near- Earth space and at extragalactic distances. The objects routinely detected by MMT-9 include faint meteors and artificial Earth satellites.We discuss astronomical tasks that can be solved using MMT-9, and present the results of the first two years of its operation. In particular, we report the parameters of the optical flare detected on June 25, 2016, which accompanied the gamma-ray burst GRB160625B.

We performed new observations of an ultra-fast rotator of th e spectral class K – the LO Peg star – in SAO RAS in 2014 and in Zvenigorod Observatory of INASAN in 2015. The light curves were used to build the maps of temperature inhomogeneities on the LO Peg surface in order to determine the longitudes corresponding to the location of active regi ons. The obtained measurements suggest the ongoing evolution of movements of active regions and pro bably the cyclic character of such movements. According to our estimations, the area of the sta r surface covered with spots decreases and by now it reached 14% of the total visible area of its surfa ce. New observations of the star in V filter allowed us to specify LO Peg long-term variability cyc les. Based on spectropolarimetric observations of LO Peg the null result for measurements of me an longitudinal component of magnetic field is obtained.

Системы широкоугольного оптического мониторинга субсекундного временнóго разрешения для обнаружения и исследования космических угроз, Бескин Г.М., Карпов С.В., Плохотниченко В.Л., Бондарь С.Ф., Перков А.В., Иванов Е.А., Каткова Е.В., Сасюк В.В., Шерер Э.