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.

В Кисловодcкой обсерватории ИНАСАН на плато Шаджатмаз начались регулярные наблюдения на фотометриче- ском комплексе для исследования транзитов экзопланет, построенном на основе телескопа Астросиб RC500 с при- емником излучения ZWO ASI6200MM Pro и колесом фильтров UBVRI. В конце 2023 и начале 2024 г. проведены наблюдения 10 транзитов экзопланет и одного кандидата в затменные переменные с пульсирующим компонентом 2MASS J23453766+713436. Проведены оценки максимальной проницающей величины фотометрического комплекса. При экспозиции 120 с в фильтрах R и V с SN R = 20 уверенно обнаруживаются объекты 19 m . При экспозициях 90 с в фильтрах V и R при SN R = 10 зафиксированы объекты 18.2 m и 19 m , соответственно. В идеальных услови- ях (нет облаков, дымки, ветра, хорошее качество изображений) для звезд с R = 13 m достигается точность (RMS) 3.5–4.0 mmag. Для более ярких объектов (R = 11 m ) достигается точность около 1.0 mmag при усреднении измерений с шагом 3 мин. Индивидуальные измерения имеют точность около 1.9 mmag. Regular observations started on photometric complex for studying exoplanet transits, located at the Kislovodsk Observatory of INASAN on the Mount Shatdzhatmaz. Its construction is based on the Astrosib RC500 telescope equipped with a ZWO ASI6200MM Pro camera and a UBVRI filter wheel. At the end of 2023 and the beginning of 2024, observations of 10 transits of exoplanets and 2MASS J23453766+713436, the eclipsing variable with a pulsating component candidate, were carried out. The maximum apparent magnitude of the photometric complex has been estimated. Objects of 19 m are reliably detected with SN R = 20 at the exposure of 120 sec in filters R and V. At exposures of 90 s in filters V and R objects of 18.2 m and 19 m respectively were recorded with SN R = 20.

The results of new photometric observations of the chromospherically active star ET Dra, performed using telescopes of the Zvenigorod INASAN Observatory, the Russian-Cuban Observatory in the territory of the Republic of Cuba (Havana), and the Terskol INASAN Observatory (a total of 8 sets of observations) with the addition of archival observations of the Kamogata Wide-field Survey. Variations in the shape of the light curve caused by the rotational modulation of a star with spots on the surface, as well as studies of the long-term variability of the star’s brightness, were investigated based on the data acquired in 2018–2023. Characteristic changes in the ET Dra light curve were noted including a decrease of the stellar brightness in the V filter, its cyclic variations, and subsequent brightness increase. The shape of the phase curve and the duration of the extended minimum of brightness vary. During the HJD 245 9670–245 9715 interval, the amplitude of the star’s brightness variability reached a maximum value of more than 0.4m, as it was in 1990. The surface temperature inhomogeneities maps were calculated and estimates of the spottedness parameter S of the object were performed for each of the 8 sets of observations. Maximum value of parameter S was 32.2‒33.5

We present the results of our photometric observations of the chromospherically active star FK Com (prototype of its group of stars) acquired during the recent 5 years (2018–2023) at the INASAN observatories in Zvenigorod and Simeiz and at the Russian–Cuban observatory in Habana (Republic of Cuba). In total, we obtained 9060 estimates of the star’s brightness in the V filter between 2018 and 2023. Our measurements, as well as data from the literature and from the Kamogata Wide-field Survey (KWS) archive, were combined into a unified set containing 17 653 measurements for a time interval about 57 years long. Based on the power spectrum derived from these data, we identified possible activity cycles P_cycl , estimated by us to be 2.4, 5.63, 8, 13.6, 30, and 49 years. The dominating P_cycl is 5.63 years long. We show that the dominating cycle found by us from extensive data to be about 5.63 years (5.4–5.8 years from other sources in the literature) can also be noticed from the analysis of earlier studies. We compared our results on the activity cycles of FK Com to data on long-term variations of two other stars of the same type, HD 199178 (V1794 Cyg) and ET Dra. Data on P_cycl of other chromospherically active stars (from the literature and from our measurements) were used to analyze the log (1/P_rot)-log (P_cycl/P_rot) diagram. We make a conclusion on the compatibility of our determinations of activity cycles for stars of the FK Com type with data for RS CVn stars.

В статье обсуждается стратегия и методика поиска экзопланет в рассеянных скоплениях на роботизированных теле- скопах ИНАСАН транзитным методом. Из-за высокой звездной плотности и расположению вблизи плоскости Галак- тики рассеянные скопления не всегда могут успешно наблюдаться космической миссией TESS, однако могут быть легко исследованы на небольших наземных телескопах. В рамках нашей программы мы проводим фотометрический мониторинг избранных площадок в близких рассеянных скоплениях на роботизированном телескопе Astrosib RC500. В результате обработки планируется выявить звезды-кандидаты, демонстрирующие периодические вариации блес- ка, по форме и амплитуде соответствующие транзитам экзопланет. В случае обнаружения таких кандидатов будет развернута программа подтверждения путем фотометрических, спектроскопических и спекл-интерферометрических наблюдений на российских телескопах. Также в результате реализации программы будут исследованы уже известные переменные звезды наблюдаемых скоплений и обнаружены новые. In this paper we discuss the strategy and methodology of searching for exoplanets in open clusters on INASAN robotic telescopes using the transit method. Due to the high stellar density and location near the galactic plane, open clusters cannot always be successfully observed by the TESS space mission, but can be easily studied with small ground-based telescopes. As part of our program, we conduct photometric monitoring of selected fields in nearby open clusters on the Astrosib RC500 robotic telescope. As a result of processing, it is planned to identify candidate stars demonstrating periodic brightness variations, corresponding in shape and amplitude to exoplanet transits. If such candidates are found, a confirmation program will be launched by photometric, spectroscopic and speckle interferometric observations on Russian telescopes. Also, as a result of the program implementation, already known variable stars of the observed clusters will be studied and new ones will be discovered.

The international collaboration between Russia and Cuba in astronomical research first began in 2017. The first 20-cm robotic telescope of the Russian-Cuban network has been operating since 2021 in Havana. The construction of the second 50-cm telescope has been underway since 2023, and it is expected to be finished and installed in 2025 near Kislovodsk (Russia). By 2030, the plan is to build the third 1-m telescope at Valle de Picadura (Cuba). We describe the main parameters and scientific equipment of the new 50-cm telescope and discuss its role in the Russian-Cuban distributed global telescope network.

Positional and multicolor photometric observations of near-Earth asteroids were carried out using the SBG telescope of the Kourovka Astronomical Observatory of Ural Federal University and the Zeiss-1000 telescope of the Simeiz Observatory of INASAN in 2022–2023. Based on the results of positional observations with the SBG telescope, improved orbital elements were obtained for seven asteroids. The periods of axial rotation of seven asteroids were estimated from photometric observations. Based on the results of photometric observations in the B, V, R, I filters, color indices were obtained for six asteroids.

Мы представляем исследование карликовой новой TCP J18173469+1803499. Она была обнаружена во время широ- копольного обзора New Milky Way (NMW) на Астроферме Астроверты, и в течение 9 ночей мы выполняли фото- метрический мониторинг этого объекта в полосах BVRI с помощью нового 50-см роботизированного телескопа Кис- ловодской обсерватории ИНАСАН. Были обнаружены сверхгорбы с периодом 0.0592 суток, которые имели малую амплитуду в начале вспышки, но на 9 сутки после начала вспышки приобрели большую амплитуду и симметричную пилообразную форму. Мы проанализировали фотометрическое поведение TCP J18173469+1803499 по результатам наших наблюдений. Наличие сверхгорбов и амплитуда вспышки, составляющая более 8 звездных величин позволяют отнести этот объект к карликовым новым типа WZ Sge. We present analysis of a dwarf nova TCP J18173469+1803499. It was discovered during the New Milky Way (NMW) wide-field survey at Astroverty astrofarm, and during 9 nights we performed photometric monitoring of this object in BVRI bands with a new 50-cm robotic telescope of Kislovodsk observatory of the Institute of Astronomy of the RAS. We detected superhumps with a period of 0.0592 days, with a small amplitude at the beginning of the outburst. However, on the 9th day after the start of the outburst they acquired a large amplitude and a symmetrical sawtooth shape. We analyzed the photometric behavior of TCP J18173469+1803499 based on our observations. The presence of superhumps and a flare amplitude of more than 2 magnitudes allow us to classify this object as a dwarf nova of the WZ Sge type.

New high-precision photometric measurements of the V957 Cep system ( P = 1.99^d , V = 11.17^m , e = 0.127 , B6 V+B8 V), as well as an integrated approach to determining orbital parameters based both on photometric solutions of the light curves and the study of the course of residual deviations of the minima timings from the linear formula O - C made it possible for the first time to accurately measure the apsidal motion rate: ω̇_obs = 2.91^∘ /year, which coincided with the theoretical value under the condition of the orbital and axial rotation synchronism: ω̇_theor = 2.92^∘ /year. The physical parameters of the component stars were obtained: T_1 = 14 550 ± 300 K, M_1 = 4.0 ± 0.2 1ptM_⊙ , R_1 = 2.55 ± 0.05 1ptR_⊙ , T_2 = 12 400 ± 250 K, M2 = 3.0 ± 0.15 1ptM_⊙ , R_2 = 1.88 ± 0.05 1ptR_⊙ . This set of parameters corresponds to stars of zero age, recently descended to ZAMS. The secondary component is a pulsating variable star of the β Cephei type.

Представлены результаты анализа многоволновых наблюдений длинного космического гамма-всплеска GRB 200829A. Красное смещение всплеска \(z\approx 1.29\pm 0.04\) определено фотометрическим методом на стадии послесвечения. В гамма-диапазоне событие является одним из самых ярких (в изотропном эквиваленте) \(E_{\textrm{iso}}\gtrsim 10^{54}\) эрг. Многоцветная кривая блеска послесвечения GRB 200829A характеризуется хроматизмом и наличием плато, плавно переходящего в степенное падение потока, которое можно также интерпретировать как квазисинхронную неоднородность (вспышку). Мы предполагаем, что наличие хроматической неоднородности в послесвечении не противоречит теории структурированного джета.

We performed astrometric and multicolor photometric observations of near-Earth asteroids at the SBG telescope of the Kourovka Astronomical Observatory of the Ural Federal University and the Zeiss-1000 telescope of the Simeiz Observatory of the Institute of Astronomy of the Russian Academy of Sciences. We improved orbital elements and estimated the A 2 acceleration due to the Yarkovsky effect for asteroids (52768) 1998 OR2, (65690) 1991 DG, (159857) 2004 LJ1, (326732) 2003 HB6, (332446) 2008 AF4, (388945) 2008 TZ3, 2015 NU13 from astrometric observations with the SBG telescope. Furthermore, we estimated the axial rotation periods of the asteroids (137170) 1999 HF1, (159857) 2004 LJ1, (326732) 2003 HB6 from photometric observations with the SBG telescope. We obtained color indices for the asteroids (137170) 1999 HF1, (138127) 2000 EE14, (153591) 2001 SN263, (159857) 2004 LJ1, (326732) 2003 HB6, 2010 TV149 from multicolor photometric observations with the Zeiss-1000 telescope. Furthermore, we estimated the taxonomic classes for three asteroids, according to the color indices: the asteroid (153591) 2001 SN263 has class C, (159857) 2004 LJ1 has class S, and (326732) 2003 HB6 has class D.

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).

We present the results of our analysis of multiwavelength observations for the long gamma-ray burst GRB 200829A. The burst redshift z≈ 1.29± 0.04 has been determined photometrically at the afterglow phase. In gamma rays the event is one of the brightest (in isotropic equivalent), E_iso≳ 10^54 erg. The multicolor light curve of the GRB 200829A afterglow is characterized by chromatic behavior and the presence of a plateau gradually transitioning into a power-law decay that can also be interpreted as a quasi-synchronous inhomogeneity (flare). We assume that the presence of a chromatic inhomogeneity in the early afterglow is consistent with the model of a structured jet.

Since 2017, the Institute of Astronomy of the Russian Academy of Sciences (Russia) and the 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 robotic telescope of this network has been operated since 2021 in Havana. The construction of the second 50 cm telescope has been underway since 2023 and it is expected to be finished and installed in 2025 near Kislovodsk (Russia). According to the current plan, a third 1 m telescope will be installed in 2030 at Valle de Picadura (Cuba). In the present contribution, the main parameters and scientific equipment of the 50 cm telescope are described and its role in the Russian-Cuban distributed global telescope network is discussed.

На телескопах СБГ Коуровской астрономической обсерватории УрФУ и Цейсс-1000 Симеизской обсерватории ИНАСАН выполнены позиционные и многоцветные фотометрические наблюдения астероидов, сближающихся с Землей. По результатам позиционных наблюдений на телескопе СБГ для астероидов (52768) 1998 OR2, (65690) 1991 DG, (159857) 2004 LJ1, (326732) 2003 HB6, (332446) 2008 AF4, (388945) 2008 TZ3, 2015 NU13 получены улучшенные элементы орбит и оценки ускорения A 2 , обусловленного влиянием эффекта Ярковского. По фотометрическим наблюдениям на телескопе СБГ оценены периоды осевого вращения астероидов (137170) 1999 HF1, (159857) 2004 LJ1, (326732) 2003 HB6. По результатам фотометрических наблюдений в фильтрах B, V, R, I на телескопе Цейсс-1000 получены показатели цвета для астероидов (137170) 1999 HF1, (138127) 2000 EE14, (153591) 2001 SN263, (159857) 2004 LJ1, (326732) 2003 HB6, 2010 TV149. Для трех астероидов по данным о показателях цвета оценен таксономический тип: астероид (153591) 2001 SN263 отнесен к типу C, (159857) 2004 LJ1 - к типу S, (326732) 2003 HB6 - к типу D. We performed astrometric and multicolor photometric observations of near-Earth asteroids at the SBG telescope of the Kourovka Astronomical Observatory of the Ural Federal University and the Zeiss-1000 telescope of the Simeiz Observatory of INASAN. We improved orbital elements and estimated the A 2 acceleration due to the Yarkovsky effect for asteroids (52768) 1998 OR2, (65690) 1991 DG, (159857) 2004 LJ1, (326732) 2003 HB6, (332446) 2008 AF4, (388945) 2008 TZ3, 2015 NU13 from astrometric observations with the SBG telescope. Furthermore, we estimated the axial rotation periods of the asteroids (137170) 1999 HF1, (159857) 2004 LJ1, (326732) 2003 HB6 from photometric observations with the SBG telescope. We obtained color indices for the asteroids (137170) 1999 HF1, (138127) 2000 EE14, (153591) 2001 SN263, (159857) 2004 LJ1, (326732) 2003 HB6, 2010 TV149 from multicolor photometric observations with the Zeiss-1000 telescope. Furthermore, we estimated the taxonomic classes for three asteroids, according to the color indices: the asteroid (153591) 2001 SN263 has class C, (159857) 2004 LJ1 has class S, and (326732) 2003 HB6 has class D.

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.

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.

In this paper we present the first research results of the optical station at the Russian-Cuban observatory. The observatory includes two stations - optical and geodynamical, created by The Institute of Geophysics and Astronomy of Cuba in collaboration with The Institute of Astronomy of The Russian Academy of Sciences and the Institute of Applied Mathematics of The Russian Academy of Sciences. The main instrument of the optical station is a 20-cm wide-field robotic telescope with a CCD camera equipped with the wheel of photometric filters. We present the first photometric researches of active stars V410 Tau, FR Cnc and FK Com obtained in the late 2021 and early 2022.

We present the first detailed X-ray study and simultaneous optical observations of the active fast rotating star FR Cnc. The X-ray spectra are found to be explained by two-temperature plasma model with temperature of cool and hot components of 0.34 and 1.1 keV, respectively. The X-ray light curve in the 0.5–2.0 keV energy band is found to be rotationally modulated with the degree of rotational modulation of $$\sim$$ 17%. We have also found that the X-ray light curve is anti-correlated with the optical light and colour curves in the sense that maximum X-ray light corresponds to minimum optical light and cooler region on the surface of FR Cnc. The X-ray luminosity of FR Cnc is found to be almost consistent in the last 30 years with an average value of $$4.85\times 10^{29}$$ erg $$\hbox {s}^{-1}$$ in the 0.5–2.0 keV energy band.