Studies of Modern Star Catalogs Based on Photoelectric Observations of Lunar Occultations of Stars

et al. 2019

In this work we propose the determination of the astrophysical dynamic coordinate system’s orientation in relation to HCRF (Hipparcos Celestial Reference Frame) using photoelectric lunar occultation. The photoelectric method of recording an occultation that allows obtaining occultations moment with the accuracy up to 0.001s (i.e. 100 times more accurate than by visual method) was found to be the most accurate. Apart from the tasks of space geodesy, photoelectric observations allow carrying out other interesting researches, too. These tasks include determination of amendments to orbital longitude and latitude of the Moon and amendments to ephemeris time. The photoelectric observations of occultation are valuable materials for solving some astrophysical tasks. If one records changes in magnitude at the moment when a star is occultated by the Moon, then one may obtain diameter of the occultated star through the spectrum of those changes. Other important problems are detecting double and multiple systems of stars and measuring angular distances between their components.

Analysis of the dynamic coordinate system using photoelectric lunar occultations

Churkin

et al. 2019

The development of projective metric method for analyzing star positions

Kostina

et al. 2020

In this work, the projective geometry method was used for analyzing star clusters. When carrying out the calculation procedures, it was considered that non-linear distortion factors had been removed from the measured stars’ coordinates. Determination of stars’ proper motions is of great practical importance, as the inertial coordinate system relies on catalogues of star positions, and it is necessary to be aware of the stellar reference marks’ time shift. In the practical part of the work, the breadboard simulation of the use of the proposed method for determining stars’ proper motions is performed. At the same time, it is supposed that at 90”/mm breadboard image scale the absolute values of proper motions do not exceed 0.050” over a period of 50 years. As result, determined that the standard deviation of the calculated proper motions μα , μβ from their true value is 0.0065 arcseconds for the first model (when the proper motions of the reference “stars” are negligible and equal to 0) and 0.0072 arcseconds or the second model (when the reference stars do have real proper motions). These values indicate the high accuracy of the used method.

Structural analysis of the comet 45P/Honda based on isophote modeling

Churkin

et al. 2021

The work focuses on using the isophote method to construct a 45P/Honda comet model. At the same time, important problems were solved for modeling the physical surface of a comet and studying the structure of the cometary nucleus. This is due to the fact that, on the basis of modern studies of meteoroids, complex internal processes and dynamic phenomena on their surface have been discovered. The study of comet nuclei is of great importance, since, according to the theory of their formation, they were formed from the matter of the protoplanetary disk. Thus, modeling and analysis of the structure of various comets make it possible to create a more accurate theory of their evolution. This made it possible to evaluate the structural parameters more accurately and reliably. This allowed for the evaluation of the structural parameters more accurately and reliably. Isophotes of the nucleus, coma and tail of comet 45P/Honda were determined. Depending on the point where the comet is located on the trajectory of its orbit, one can see structural changes in the comet’s brightness from the nucleus to the peripheral region. Near the cometary nucleus, the isophotes are circular in shape. If in the center of the model the isophotes have a shape close to narrow rings, then elongations in the direction of the cometary tail and thickening of their structure appear towards the peripheral regions. Large and small tail rays can be distinguished, and the nucleus is well marked. In the future, the author’s method for modeling isophotes, developed in this work, will allow studying the structure of various cometary objects, and, based on the results, determine the degree of comet activity. On the other hand, about the development of the theory of dynamic processes and the evolution of the Solar system, one can use the data on changes in cometary activity in the process of its movement around the Sun.