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Keywords_142
Моделирование орбиты космического радиотелескопа для оценки параметров наземно-космического радиоинтерферометра в проекте "Радиоастрон"
В. Е. Жаров1, И. А. Гирин2, В. И. Костенко2, С. Ф. Лихачев2
1Государственный астрономический институт им. П. К. Штернберга, г. Москва, Россия
2Астрокосмический центр Физического института РАН им. П. Н. Лебедева, г. Москва, Россия
Аннотация:
Для обеспечения корреляционной обработки наблюдений на наземно-космическом интерферометре в проекте "Радиоастрон" ГАИШ и АКЦ ФИАН разработали навигационную модель движения космического радиотелескопа (КРТ) для вычисления задержки и изменения фазы сигнала, необходимых при управлении работой коррелятора. За основу был взят пакет АРИАДНА [1] для обработки наблюдений на наземных РСДБ. Также пакет был использован для оценки параметров наземно-космического интерферометра.
Ключевые слова:
космический радиотелескоп, орбита, интерферометр
Modeling of the Space Radio Telescope Orbit for Estimation of the Ground-space Interferometer Parameters During the Radioastron Mission
V. E. Zharov, I.A. Girin, V. I. Kostenko, S. F. Likchachev
Abstract
The RadioAstron project is an international collaborative mission to launch a satellite carrying a 10-m space radio telescope (SRT) on the elliptical orbit around the Earth. The aim of the mission is to create the ground-space VLBI to observe the radio sources with high angular resolution. The orbit of the SRT has an apogee altitude about 330,000 km, a period of 8-9 days, and an eccentricity about 0.9. The ground-space VLBI observations at a standard radio astronomical wavelength set of 1.35, 6, 18, and 92 cm with such orbit would provide information about structure of the galactic and extragalactic radio sources at microarcsecond level.
Our goal is to use the ground-space VLBI observations for the solution of some astrometric problems such as study of the defining sources structures and their variations, connection of the ICRF and dynamical system based on the pulsar timing, by means of measuring the ground telescopes coordinates relative to the center of mass of the Earth.
It was shown that the key for solution of these problems is the reconstruction of the SRT precise orbit. Model of motion of the SRT was developed for calculation of the interferometer delay and other parameters to ensure the proper work of the Astro Space Center correlator in use. The ARIADNA/ORBITA package was used as base for correlation process.
To study the parameters of the ground-space interferometer two noisy signals "received" by the ground telescope and SRT were emulated. At first step the position and velocity of the SRT were varied relative to the known (true) trajectory and then the signal to noise ratio (SNR) was changed. Correlation of signals gives us possibility to estimates such parameters of the ground-space VLBI as sensitivity and its dependence from the integration time, the coherence time and dependence from the SNR and the SRT position errors. It was shown that to ensure the mission success the different methods of SRT orbit control has to be developed and applied.
Keywords:
space radio telescope, orbit, interferometer