Since 2017 the Institute of Astronomy of the Russian Academy of Sciences (Russia) and Institute of Geophysics and Astronomy (Cuba) have been implementing a joint international project with the aim of building a distributed global optical telescope network. The first 20 cm aperture robotic telescope of the the Russian-Cuban network has been operating since 2021 in Havana. It has a 3.5x3.5 degree field of view and a FLI PL16803 4K CCD camera with a set of UBVRI photometric filters. Construction of the second 50 cm telescope near Kislovodsk (Russia) has been underway since 2023 and it will be finished at the end of 2024, its scientific operation will start in early 2025. By 2030, the plan is to build the third 1 m telescope at Valle de Picadura (Cuba). The main parameters and scientific equipment of the new 50 cm telescope are described and its role in the Russian-Cuban distributed global telescope network is discussed.

Planned for the launch in late 20s Spektr-UF space observatory, being created in Russia, is designed to obtain images and spectra of space objects in the ultraviolet region of the electromagnetic spectrum (115 - 310 nm). Here we briefly describe the current status of the mission.

Planned for the launch in late 20s Spektr-UF space observatory, being created in Russia, is designed to obtain images and spectra of space objects in the ultraviolet region of the electromagnetic spectrum (115 - 310 nm). An important part of the observatory is a special software - an exposure time calculator ( ETC). This software is necessary for planning and implementing the observatory's scientific program. It allows not only to evaluate the possibility of registering a signal from an astronomical object of interest, but also to prepare and select applications, as well as draw up an observation program. In preparation for the launch of Spektr- UF, an exposure calculator for this observatory was developed, with which users can plan photometric and spectral observations of various astronomical objects. When developing this program, the experience of other missions, primarily the Hubble Space Telescope (HST), was used. The work reviews the main capabilities of the Spektr-UF ETC and also presents a mathematical model of this calculator that characterizes the signal recording process. Based on real examples, the possibility of implementing photometry and spectroscopy modes for astronomical objects using various scientific instruments of the observatory is discussed. And some observational limits are shown. Plans for the improvement of the ETC are discussed too.

Astroclimatic conditions characterize the quality of an astronomical site. The Terskol Observatory was founded over 42 years ago in 1980. The astronomical site (coordinates 43.16'29 ''' N,42.30'03 ''' E) is located about 10 km from Mt. Elbrus in the northern Caucasus Mountains. The paper presents the results of an analysis astroclimatic parameters such as total cloud cover, precipitable water vapor, and wind speed at a level of 200 hPa. above the Terskol Observatory using atmospheric ERA5 Reanalysis data from the European Center for Medium-Range Weather Forecast, as well as acoustic station data and optical measurements. The study of seasonal changes in the astroclimate parameters: wind speed at a level of 200 mbar, as a parameter of applicability of adaptive optics (AO), altitude distribution of wind speed, which determines the requirements for AO performance, moisture content for assessing the possibility of AO operation in the IR range. The statistics of the seeing for 2023 are also provided.

The space mission "Spektr-UF" (Spectrum Ultraviolet, another name is World Space Observatory-Ultraviolet) is aimed to create a large space telescope to work in the UV wavelength domain (115 - 310nm). In the Federal Space Program of Russia the launch of the project is scheduled for 2029. For successful operation of the space mission we are preparing ground based telescopes with imaging instrumentation for 2-m and 1-m telescopes of INASAN. One of the main tasks for the ground support is a filter coordination. Work is planned to determine the characteristics for creating instruments for ground-based mission support, to develop tools for preparing applications for the observation program, to develop a program for scientific research of the project. In this paper we discuss spectroscopic and imaging instrumentations of Russian telescopes to be used as project ground support.

The Spectroscopic Investigation of Nebular Gas (SING) is a near-ultraviolet (NUV) low-resolution spectrograph payload designed to operate in the NUV range, 1400 $\unicode{x212B}$ -- 2700 $\unicode{x212B}$, from a stable space platform. SING telescope has a primary aperture of 298 mm, feeding the light to the long-slit UV spectrograph. SING has a field of view (FOV) of 1$^{\circ}$, achieving a spatial resolution of 1.33 arc minute and spectral resolution of 3.7 $\unicode{x212B}$ ($R\sim600$) at the central wavelength. SING employs a micro-channel plate (MCP) with a CMOS readout-based photon-counting detector. The instrument is designed to observe diffuse sources such as nebulae, supernova remnants, and the interstellar medium (ISM) to understand their chemistry. SING was selected by the United Nations Office for Outer Space Affairs to be hosted on the Chinese Space Station. The instrument will undergo qualification tests as per the launch requirements. In this paper, we describe the hardware design, optomechanical assembly, and calibration of the instrument.

Spektr–UF (World Space Observatory Ultraviolet, WSO-UV) is a Russian-led international collaboration aiming to develop a large space-borne 1.7 m Ritchey–Chretién telescope with science instruments to study the Universe in ultraviolet wavelengths. The WSO-UV spectrograph (WUVS) consists of three channels: two high-resolution channels (R = 50,000) with spectral ranges of 115–176 nm and 174–310 nm, and a low-resolution (R = 1000) channel with a spectral range of 115–305 nm. Each of the three channels has an almost identical custom detector consisting of a CCD inside a vacuum enclosure, and drive electronics. The main challenges of the WUVS detectors are to achieve high quantum efficiency in the FUV-NUV range, to provide low readout noise (3 e− at 50 kHz) and low dark current (<12 e−/pixel/hour), to operate with integral exposures of up to 10 h and to provide good photometric accuracy. A custom vacuum enclosure and three variants of a custom CCD272-64 sensor with different UV AR coatings optimised for each WUVS channel were designed. The enclosure prevents contamination and maintains the CCD at the operating temperature of −100 ∘C, while the temperature of the WUVS optical bench is +20 ∘C. A camera electronics box (CEB) that houses the CCD drive electronics was developed. Digital correlated double sampling technology allows for extremely low readout noise and flexible frequency for normal and binned pixel readout modes. This paper presents the WUVS detector design drivers, methods for extending the service life of the CCD sensors working with low signals in a space radiation environment and the key calculated parameters and results of the engineering qualification model qualification campaign.

The star KIC 2142183, which was previously noted as a rapidly rotating giant with flare activity, was studied based on the analysis of photometric observations with the Kepler space telescope. We have estimated the spottedness parameter S for KIC 2142183 (5–14% of the entire visible surface area of the star) and differential rotation (the $$\Delta \Omega $$ parameter is in the range of 0.022–0.068 rad/day). KIC 2142183 has a high flare activity: the literature contains information on 100 flares with energies log E in the range from 34.8 to 36.3. The results of the study and the data available in the literature suggest that KIC 2142183 is a likely candidate for an FK Com star. It was concluded that the characteristics (rotation, flare activity, and spot activity) of the giants KIC 2142183 and the candidate KIC 6428626 studied previously are in fairly good agreement. The area of spots on the surface of both giant stars in absolute terms not only significantly exceeds the total area of spots on the Sun, but is larger than the entire visible surface area of the Sun. Both stars have high flare activity.

In the current era when access to space is becoming easier and at a lower cost thanks to the standardised cubesat technology, numerous missions are expected to be launched to observe, particularly, at ultraviolet wavelengths. Given the reduced dimensions of the telescope that a cubesat can carry, most of these missions will be focused on photometric surveys of a reduced sample of targets of interest, and therefore each mission will define their own photometric bands according to their scientific objectives and orbital constraints. However, in order to provide a coherent view of the ultraviolet sky, the data should be post-processed under a common framework. In 2017, the IAU working group on ultraviolet astronomy identified the need to define such a common framework for the upcoming ultraviolet missions, and coordinated the definition of a standard set of photometric bands that could serve for homogenizing the current and future data. This paper presents the procedure adopted by the working group for the definition of the standard photometric system, that was approved by the IAU during the General Assembly Business Sessions held in August, 2021. The photometric system consists of seven bands, denoted as UV1-UV7, all included in the range 115 - 400 nm. Some of these bands are based on existing filters, while others have been defined as theoretical bands with constant throughput. This system is to be regarded as a set of synthetic bands for post-processing the data of any mission, and an example of its application to the SPARCS cubesat is also included. The photometric bands are publicly available and can be downloaded from https://www.nuva.eu/uv-photometry/ .

Observational data in the ultraviolet wavelength region of the electromagnetic spectrum (120-300 nm) are a powerful tool for studying many astrophysical objects such as exoplanets, especially for determining the characteristics of their atmospheres. Numerous publications on exoplanetary research in leading astronomical publications, prepared in recent years on the basis of realized applications for observations on the instruments of the Hubble Space Telescope (HST), which is the main telescope for spectroscopy in UV, indicates its high demand by the astronomical community. Work is underway to create an orbital space observatory "Spektr-UF" (World Space Observatory - Ultraviolet), which will be the successor of the HST. The Institute of Astronomy RAS is the Lead scientific organization for this project and University Complutense of Madrid is the main WSO-UV partner. Within the framework of this research, work is planned to determine the characteristics for creating instruments for ground-based mission support, to develop tools for preparing applications for the observation program, to develop a program for scientific research of the project. In this paper we discuss spectroscopic and imaging instrumentations of Russian telescopes to be used as project ground support.

The mission Ultraviolet Researcher to Investigate the Emergence of Life (URIEL) is designed to carry out low dispersion (600-1,000) UV spectropolarimetry in the 140-400 nm spectral range to investigate the formation of planetary systems, its interaction with stellar winds and search for signatures of prebiotic molecules by remote sensing of small bodies in the Solar System (comets and meteorites) in near Earth orbit. URIEL is conceived as a 50cm primary telescope with a RitcheyChrétien mounting. The telescope is equipped with a single instrument, the ultraviolet spectropolarimeter, whose low dispersion will enable resolving the main spectral features whilst guaranteeing enough flux per resolution element for the Stokes parameters to be measured to an accuracy of 500 ppm in the full range. According to recent calculations based on the chemical analysis of meteorites, this accuracy suffices for the remote detection of alanine by its optical activity at 180 nm in nearby minor bodies. In this sense, URIEL is a pathfinder mission to the technology that will enable remote sensing of amino acids and addressing the source of the chirality imbalance in Earth's bio-molecules.

Сформулированы преимущества размещения астрономического телескопа на Луне. Предложен ряд актуальных научных задач. Представлены три различных подхода к созданию астрономического телескопа на будущей международной научной лунной станции

The World Space Observatory–Ultraviolet mission (Spektr-UF, WSO-UV) is an efficient multipurpose orbital observatory for high- and low-resolution spectroscopy, high sensitivity imaging and slitless spectroscopy in the ultraviolet wavelength range. It will open new opportunities in (exo)planetary science, extragalactic astronomy, stellar astrophysics and cosmology. The observatory is based on a complex of scientific instruments including the T-170M telescope (aperture 170 cm), spectrographs and imagers. The payload should be ready in 2025. We briefly describe the current status of the mission.

Представлены результаты новых спектральных наблюдений хромосферно-активной звезды FK Com в 2021 и 2022 г. в Симеизской обсерватории и в обсерватории Синлонг (Xinglong, NAOC, Китай). Рассмотрена эволюция профилей линии H α в спектре FK Com. Новые наблюдения показали, что зарегистрированные нами изменения формы профилей линии H α аналогичны опубликованным ранее в литературе. По нашим спектрограммам, полученным для фаз вращения звезды близким к 0.7 с интервалом около года (в 2021 и 2022 г.) и полученным на обсерваториях KPNO (в 2000 г.) и NOT в 1998, 1999, 2001, 2003, 2004 г. для этой же фазы, установлены различия в профилях линии H α . Вероятно, изменения профилей линии H α в большей степени зависят от уровня активности звезды, чем от фазы вращения. We present the results of new spectral observations of the chromospherically active star FK Com in 2021 and 2022 at the Simeiz Observatory and the Xinglong Observatory (NAOC, China). The evolution of the pro les of the H α line in the spectrum of FK Com is considered. New observations indicate that the changes in the shape of the pro les of the H α line registered by us are similar to those previously published in the literature. According to our spectra obtained for the phases of rotation of the star close to 0.7 with an interval of about a year (in 2021 and 2022) and obtained at the KPNO (2000) and NOT observatories in 1998, 1999, 2001, 2003, 2004 for the same phase, di erences in the pro les of the H α line are established. Probably, the changes in the pro les of the H α line depend more on the level of activity of the star than on the phase of rotation.

The advantages of an astrophysical UV telescope on the Moon surface and a number of scientific tasks are discussed. An approach to build an astronomical 20-30 cm UV telescope at the future International Lunar Research Station is presented. It is suggested to use a slewing mirror to repoint the Moon-based telescope and to switch between filters and detectors. The first small telescope at the ILRS can be considered as a step towards the development of technologies for Moon-based astronomical observations.

Статья посвящена проекту «Спектр-УФ», который развивается, используя имеющийся запас времени до его запуска. Изложен текущий статус проекта, при этом акцент сделан на появившихся изменениях в проекте. The article presents an overview of the Spektr-UF project, which is outlines the current status of the project, with emphasis on the changes that have appeared in the project.

We present information about the first results of work on the study of stars at the optical station of the Russian–Cuban Observatory. The observatory consists of two stations – optical and geodynamic, created by the Institute of Astronomy of the Russian Academy of Sciences and the Institute of Applied Astronomy of the Russian Academy of Sciences together with the Institute of Geophysics and Astronomy of the Republic of Cuba. The main instrument of the observatory is a 20-cm wide-field robotic telescope with a CCD camera and a photometric filter wheel. In late 2021 and early 2022, the first photometric studies of the active stars V410 Tau and FR Cnc were carried out.

Beginning of operation of the first Russian–Cuban Observatory telescope, a wide-field 20-cm robotic telescope installed at the observational site optical station in Havana, Republic of Cuba, is reported. The general view of the telescope is shown and attached equipment is described. The “first light” obtained using a 20-cm telescope is demonstrated and briefly discussed. Multi-task observational projects supposed to be conducted using mentioned RCO telescope are described. Russian–Cuban complexication scheme is described and some of its features are briefly discussed.

OUL is a wide field imager designed as a small, additional payload to be attached to the Luna 26 mission. The instrument has a field of view of 20° × 20° and provides images with angular resolution 3 arcmin in several far ultraviolet bands, including Lyman-α, He II at 164nm and several continuum bands. The imager is designed to monitor the Earth’s exosphere and the ecliptic (+/-20°) primary at Lyman-α and in the 125-140 nm and 145-170 nm bands. In this contribution, the optical design of the instrument, its mechanical layout and the science program to be implemented will be described.