In 2022, the telescope of the Main (Pulkovo) Astronomical Observatory of RAS obtained astrometric and photometric series of observations of a potentially dangerous asteroid (138971) 2001 CB21 during its approach to Earth. Based on the data obtained and data from the MPC website, the asteroid’s orbit was improved and the circumstances of the encounters were investigated with the Earth and Venus and an assessment was made of the influence of nongravitational effects on its motion. Based on photometric observations of the asteroid, a light curve was constructed and its axial rotation period was confirmed: R = 3.305 ± 0.002 h.

In 2020, two telescopes of the State Astrophysical Observatory of the Russian Academy of Sciences, ZA-320M and MTM-500M, obtained series of observations of the potentially dangerous asteroid 65690 (1991 DG) during its approach to the Earth and carried out their astrometric and photometric processing. Using the coordinates of the asteroid and observations from the MRS site, the orbit of the asteroid was clarified, and the circumstances of the approaches to the Earth and Mars were determined, and an assessment was made of the influence of nongravitational effects on its orbit. Based on the results of photometric processing of the asteroid, a light curve was constructed and the period of its axial rotation was determined: P = 4.3193 ± 0.0028 h.

Представлены результаты выявления астероидов, потенциально опасных для внутренних планет. Исследовано орбитальное движение астероида 2022 АЕ1, троянцев Земли (2010 TK7, 2020 XL5) и «рукотворного» астероида 2020 SO. The results of the detection of potentially hazardous asteroids for the inner planets are presented. The orbital motion of asteroid 2022 AE1, the Earth Trojans (2010 TK7, 2020 XL5), and the “man-made” asteroid 2020 SO has been studied.

The groups of asteroids which can have approaches to two or more planets have been determined. It is shown that in the phase space of the orbital elements there are regions in which asteroids can be for a long time, potentially hazardous for all the inner planets of the Solar System at the same time. Further study of such objects is necessary, including obtaining new observations.

The astrometric and photometric series of observations of potentially hazardous asteroid (276033) 2002 AJ129 were obtained with MTM-500M telescope of Pulkovo Observatory in the period of its close approach to the Earth on February 4, 2018. The orbital evolution was studied and the influence of non-gravitational effects (solar ra-diation pressure and the Yarkovsky effect) was estimated. The axial rotation period (P = 3.9222 +/- 0.0008 h) of the asteroid and the color indices (B-V = 0.687 +/- 0.050, V-R = 0.405 +/- 0.027, R-I = 0.178 +/- 0.044) were determined from the photometric series of observations.

The asteroid (13553) Masaakikoyama was observed with the ZA-320M and MTM-500M telescopes of the Pulkovo observatory in August and September 2018. Its axial rotation period was estimated based on the observed sections of the light curve (and additional observational data provided by B.D. Warner) at 97.2 ± 0.3 h. This estimation was made difficult by the fact that the period is commensurable with a day. The light curve has certain features suggestive of tumbling rotation and a complex shape. The orbit of (13553) Masaakikoyama was improved using the obtained astrometric positions of the asteroid.

Observations of potentially hazardous asteroid 2017 VR12 during its close approach to the Earth were made at Pulkovo Observatory via ZA-320M telescope at the end of February and the beginning of March 2018. Orbital elements of the asteroid were improved basing on the obtained astrometric data. The orbital evolution was studied and the influence of non-gravitational effects was estimated. The axial rotation period of the asteroid was determined from photometric data.

In 2017, Pulkovo observatory organized two campaigns of baseline observations of two asteroids during their approaches to the Earth: 2014 JO25 (on April) and (418094) 2007 WV4 (on June). The goal of the campaigns was development of method of construction of precise asteroid orbits using short-time (1-2 hours) simultaneous observations from two observatories (triangulation method). Six observatories participated in the 2017 campaigns: Ussuriisk Astrophysics Observatory of RAS, Gissar and Sanglokh observatories of Institute of Astrophysics of Tajikistan, Zvenigorod Observatory of Institute of Astronomy of RAS, Pulkovo Observatory of RAS, Mountain Astronomical Station of Pulkovo Observatory. The orbit constructed with this method for 2014 JO25 asteroid is close to the orbit published on the MPC web-site that was constructed with more than 1.5 thousand observations of many observatories from 2011 to 2017. The results of the campaigns show that given existing accuracy of astrometric measurements, simultaneous observations of two observatories during more than 1 hour and the parallax angle of more than 10 arcmin are needed to construct sufficiently precise orbit. Also, the estimation of BVRI color indices of 2014 JO25 asteroid was made.

Using the telescopes ZA-320 M and MTM-500 M of Pulkovo Observatory (Russia), we have carried out astrometric and photometric observations of the asteroid (367943) Duende (2012 DA14) immediately after its close approach to the Earth occurred on 2013 February 15. We have obtained a series of its astrometric positions, colour indices and two fragments of its light curve. By numerically integrating, we have studied the evolution of the asteroid's orbit. Also, the influence of solar radiation pressure and Yarkovsky effect on the asteroid was estimated. The fitting of the asteroid rotation model to the observed light curve indicates that during its closest approach to the Earth, it had tumbling rotation regime.

The use of ground-based and space baseline observations of Solar System bodies is considered. Baseline observations allow one to determine the distance to observed objects and (in some cases) the parameters of their orbital motion. Certain results of baseline observations of near-Earth asteroids and the results of model analysis of spacecraft observations are presented.

Observational Astrometry Laboratory and Ephemeris Provision Sector of Pulkovo Observatory carry out a joint multipurpose research on asteroids belonging to various groups. Astrometric and photometric observations are done using ZA–320M and MTM–500M telescopes located at Pulkovo and in Northern Caucasus mountains, correspondingly. We obtain lightcurves that allow us to determine spin parameters and shapes of asteroids. Their color indices and taxonomy classes are derived from wideband filter observations. Improvement of asteroid orbits is achieved by doing positional measurements. Orbital evolution of asteroids is modelled, taking into account also non-gravity forces, including light pressure and Yarkovsky effect. NEAs, as well as binary asteroids, take an important place in our investigations. Quasi-satellites of Venus, Earth, and Mars are new targets of our research, one of the examples being 2012DA14 that approached Earth in early 2013; many MTM–500M observations of this asteroid were obtained around the date of approach.

На автоматизированных телескопах Пулковской обсерватории ЗА-320М и МТМ-500М в период, соответствующий максимальному сближению астероида (308635) 2005 YU55 с Землей, с 9 по 20 ноября 2011 г., были проведены его астрометрические и фотометрические наблюдения. Была определена измененная после тесного сближения с Землей новая орбита астероида. На основе данной орбиты было предвычислено тесное сближение с Венерой 19 января 2029 г. с оценкой расстояния в момент максимального сближения – 359 тыс. км. На основе анализа полученных фотометрических данных был уточнен период осевого вращения астероида, который составил 16.3 ± 0.4 ч. Получены оценки показателей цвета астероида B–V, V–R и R–I, на основе которых был определен таксономический класс астероида – B. Кроме того, из полученных нами фотометрических наблюдений астероида было обнаружено неизвестное ранее изменение блеска с периодом 0.9–1.2 ч, причина которого до конца не изучена.

Astrometric and photometric observations of asteroid (308635) 2005 YU55 were carried out at the computer-aided ZA-320M and MTM-500M telescopes of the Pulkovo observatory in the period of its closest approach to the Earth, from November 9 to 20, 2011. The new orbit of the asteroid changed after its close approach to the Earth was determined. From this orbit, a close approach to Venus on January 19, 2029, was precalculated, and the distance at the closest approach—359000 km—was estimated. From the analysis of the acquired photometric data, the axial rotation period of the asteroid was more accurately determined, and it amounted to 16.3 ± 0.4 h. The color indexes of the asteroid, B-V, V-R, and R-I, were estimated, which allowed the taxonomic class of the asteroid, B, to be determined from them. In addition, from our photometric observations of the asteroid, the earlier unknown change in its brightness with a period of 0.9–1.2 h was detected; the cause of this change has not been completely studied yet.

Formulation of the Orbital Stellar Stereoscopic Observatory (OSSO) project is presented. The project assumes allocation of two identical space probes in the vicinity of the L4 and L5 Sun-Earth Lagrangian points. Phase A is presented.