Paper (*cross-listing*): gr-qc/0007007

Date: Wed, 5 Jul 2000 17:15:54 GMT (7kb)

Title: Numerical Data-Processing Simulations of Microarcsecond Classical and
Relativistic Effects in Space Astrometry

Authors: Sergei M. Kopeikin (University of Missouri-Columbia, USA), N.V.
Shuygina, M.V. Vasilyev, E.I. Yagudina (Institute of Applied Astronomy,
Russia), L.I. Yagudin (Pulkovo Observatory, Russia)

Categories: gr-qc

Comments: 5 pages, the talk given at the IAU Coll. 180 "Towards Models and
Constants for Sub-Microarcsecond Astrometry", Washington DC, March 26 - April
2, 2000
\\
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 between the spacecraft, geocentric, and
solar barycentric reference systems allowing unique and unambiguous
interpretation of the stellar aberration and parallax effects. On the other
hand, the algorithm must also 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
particular cases the gravitomagnetic field induced by the translational motion
of the Sun and planets should be also taken into account for unambigious
prediction of the light-ray deflection angle. In the present paper we describe
the corresponding software program for taking into account all classical
(proper motion, parallax, etc.) and relativistic (aberration, deflection of
light) effects up to the microarcsecond threshold and 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.

\\ ( http://arXiv.org/abs/gr-qc/0007007 , 7kb)

Paper (*cross-listing*): gr-qc/0011031

Date: Wed, 8 Nov 2000 23:35:23 GMT (15kb)

Title: Theory of Relativistic Reference Frames for High-Precision Astrometric
Space Missions

Authors: Sergei M. Kopeikin (University of Missouri-Columbia, USA)

Categories: gr-qc

Comments: Plenary talk submitted to the Proceedings of the Spanish Relativity
Meeting, ERE2000; 12 pages
\\
Recent modern space missions deliver invaluable information about origin of
our universe, physical processes in the vicinity of black holes and other
exotic astrophysical objects, stellar dynamics of our galaxy, etc. On the other
hand, space astrometric missions make it possible to determine with
unparalleled precision distances to stars and cosmological objects as well as
their physical characteristics and positions on the celestial sphere.

Permanently growing accuracy of space astronomical observations and the urgent
need for adequate data processing algorithms require corresponding development
of an adequate theory of reference frames along with unambiguous description of
propagation of light rays from a source of light to observer. Such a theory
must be based on the Einstein's general relativity and account for numerous
relativistic effects both in the solar system and outside of its boundary. The
main features of the relativistic theory of reference frames are presented in
this work. A hierarchy of the frames is described starting from the perturbed
cosmological Friedmann-Robertson-Walker metric and going to the observer's
frame through the intermediate barycentric and geocentric frames in the solar
system. Microarcsecond astrometry and effects of propagation of light rays in
time-dependent gravitational fields are discussed as well.

\\ ( http://arXiv.org/abs/gr-qc/0011031 , 15kb)

Astrophysics, abstract
astro-ph/0603265

From: Pankaj Jain [view email]

Date: Fri, 10 Mar 2006 11:59:00 GMT (181kb)

Interferometric Parallax: A Method for Measurement of Astronomical Distances

Authors: Pankaj Jain, John P. Ralston

Comments: 4 pages, 1 figure

We show that distances of objects at cosmological distances can be measured directly using interferometry. Our approach to interferometric parallax comes from analysis of 4-point amplitude and intensity correlations that can be generated from pairs of well-separated detectors. The baseline required to measure cosmological distances of Gigaparsec order are within the reach of the next generation of space-borne detectors. The semi-classical interpretation of intensity correlations uses a notion of a single photon taking two paths simultaneously. Semi-classically a single photon can simultaneously enter four detectors separated by an astronomical unit, developing correlations feasible to measure with current technology.

http://arxiv.org/abs/astro-ph/0603265