Numerical Data-Processing Simulation of Microarcsecond Classical and Relativistic Effects in Space Astrometry

• Main Authors: Kopeikin, Sergei M, Shuygina, N V, Vasilyev, M V, Yagudina, E I, Yagudin, L I
• Format: Report
• Language: English
• Subjects: ALGORITHMS; ARTIFICIAL SATELLITES; ASTROMETRIC DATA; Astronomy; BRS(BARYCENTRIC REFERENCE SYSTEM); Celestial Mechanics; Computer Programming and Software; COMPUTER PROGRAMS; COMPUTERIZED SIMULATION; DATA PROCESSING; DATA REDUCTION; EARTH ORBITS; ERA(EPHEMERIDES RESEARCH IN ASTRONOMY COMPUTER PROGRAM); GRS(GEOCENTRIC REFERENCE SYSTEM); INTERFEROMETRY; LIGHT DEFLECTION; LIGHT TRANSMISSION; MICROARCSECOND PRECISION; MONTE CARLO METHOD; MOTION; OBSERVATION; OPTICAL DATA; OPTICAL INTERFEROMETERS; Optics; PARALLAXES; PLANETS; POSITION(LOCATION); PROPER MOTION; RADIAL VELOCITY; RELATIVITY THEORY; SATELLITE ASTROMETRY; SPACE ASTROMETRY; SPACEBORNE; SRS(SATELLITE REFERENCE SYSTEM); STARS; STELLAR ABERRATIONS; SYMPOSIA; TELESCOPES; VELOCITY

The accuracy of astrometric observations conducted via a space-borne optical interferometer orbiting the Earth is expected to approach a few microarcseconds. Data processing of such extremely high-precision measurements requires access to a rigorous relativistic model of light ray propagation developed in the framework of General Relativity. The data processing of the space interferometric observations must rely upon the theory of general-relativistic transformations among the spacecraft, geocentric, and solar barycentric reference systems, allowing unique and unambiguous interpretation of the stellar aberration and parallax effects. The algorithm used also must include physically adequate treatment of the relativistic effect of light deflection caused by the spherically symmetric (monopole-dependent) part of the gravitational field of the Sun and planets as well as the quadrupole- and spin-dependent counterparts of it. In some cases the gravitomagnetic field induced by the translational motion of the Sun and planets also should be taken into account for unambiguous prediction of the light ray deflection angle. In this paper, the authors describe the corresponding software program that takes into account all classical (proper motion, parallax, etc.) and relativistic (aberration, deflection of light) effects up to the microarcsecond threshold. They demonstrate using numerical simulations how observations of stars and/or quasars conducted on board a space optical interferometer orbiting the Earth can be processed and disentangled. For simulation purposes, the spacecraft orbital parameters and the telescope optical system characteristics are similar to those in the Hipparcos mission. Numerical data analysis verifies that the relativistic algorithm chosen for data processing is convergent and can be used to determine astronomical coordinates and proper motions of stars with the required microarcsecond precision. Presented at the International Astronomical Union (IAU) Colloquium (180th) Towards Models and Constants for Sub-microarcsecond Astrometry held at the U.S. Naval Observatory in Washington, DC on 27-30 Mar 2000. Pub. in Proceedings of IAU Colloquium 180, p320-326, 2000. Prepared in collaboration with the Institute of Applied Astronomy and the Pulkovo Observatory, St. Petersburg, Russia.