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MultiView High Precision VLBI Astrometry at Low Frequencies

Published online by Cambridge University Press:  16 July 2018

M. Rioja ,
R. Dodson ,
G. Orosz  and
H. Imai
M. Rioja
Affiliation:
International Centre for Radio Astronomy Research, UWA, 7 Fairway, Western Australia CSIRO Astronomy and Space Science, 26 Dick Perry Avenue, Kensington WA 6151, Australia Observatorio Astronómico Nacional (IGN), Alfonso XII, 3 y 5, 28014 Madrid, Spain
R. Dodson
Affiliation:
International Centre for Radio Astronomy Research, UWA, 7 Fairway, Western Australia
G. Orosz
Affiliation:
Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan
H. Imai
Affiliation:
Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan Science and Engineering Area of Research and Education Assembly, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan
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Abstract

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Observations at low frequencies (<8GHz) are dominated by distinct direction dependent ionospheric propagation errors, which place a very tight limit on the angular separation of a suitable phase referencing calibrator and astrometry. To increase the capability for high precision astrometric measurements an effective calibration strategy of the systematic ionospheric propagation effects that is widely applicable is required. The MultiView technique holds the key to the compensation of atmospheric spatial-structure errors, by using observations of multiple calibrators and two dimensional interpolation. In this paper we present the first demonstration of the power of MultiView using three calibrators, several degrees from the target, along with a comparative study of the astrometric accuracy between MultiView and phase-referencing techniques. MultiView calibration provides an order of magnitude improvement in astrometry with respect to conventional phase referencing, achieving ~100micro-arcseconds astrometry errors in a single epoch of observations, effectively reaching the thermal noise limit.

Keywords

astrometry - techniques: high angular resolution - techniques: interferometric
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S336: Astrophysical Masers: Unlocking the Mysteries of the Universe , September 2017 , pp. 439 - 442
Copyright
Copyright © International Astronomical Union 2018 

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