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Models for Source Structure Corrections

Published online by Cambridge University Press:  12 April 2016

P. Charlot
P. Charlot*
Affiliation:
Observatoire de Bordeaux - CNRS/UMR 5804, 2 rue de l’Observatoire, BP 89, 33270 Floirac, France

Abstract

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At the milliarcsecond scale, most of the extragalactic radio sources exhibit spatially-extended intrinsic structures which are variable in both time and frequency. Such radio structures set limits on the accuracy of source positions determined with the Very Long Baseline Interferometry (VLBI) technique unless their effects in the astrometric data can be accounted for. We review the modeling scheme for calculating source structure corrections and discuss the magnitude and impact of these effects for the sources that are part of the International Celestial Reference Frame (ICRF). Results obtained by applying source structure corrections to actual VLBI observations on the time-varying source 4C39.25 (0923 + 392) are also presented.

Type
Section 1. Celestial Reference System and Frame
Information
International Astronomical Union Colloquium , Volume 180: Towards Models and Constants for Sub-Microarcsecond Astrometry , March 2000 , pp. 29 - 39
Copyright
Copyright © US Naval Observatory 2000

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