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VLBI Astrometry of the Ultra-Compact Nucleus of M81

Published online by Cambridge University Press:  12 April 2016

A. Ebbers ,
N. Bartel ,
M. F. Bietenholz ,
M. P. Rupen  and
A. J. Beasley
A. Ebbers
Affiliation:
York University & Dominion Radio Astrophysical Observatory, Penticton, B.C., Canada
N. Bartel
Affiliation:
York University, North York, Ont., Canada
M. F. Bietenholz
Affiliation:
York University, North York, Ont., Canada
M. P. Rupen
Affiliation:
National Radio Astronomy Observatory, Socorro, NM, U.S.A.
A. J. Beasley
Affiliation:
National Radio Astronomy Observatory, Socorro, NM, U.S.A.

Abstract

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M81 has been shown to have a compact flat-spectrum core with a possible steep-spectrum jet. We report on position determinations of the brightness peak of the nucleus relative to the position of the early supernova 1993J with uncertainties as low as 0.08 mas. At early epochs, the supernova was largely pointlike at any frequency and therefore an ideal phase reference. We describe how VLBI astrometry at several frequencies could be used to support a model with a core and a one-sided jet for the nucleus of M81.

Information

Type
Research Article
Information
International Astronomical Union Colloquium , Volume 164: Radio Emission from Galactic and Extragalactic Compact Sources , 1998 , pp. 203 - 204
Copyright
Copyright © Astronomical Society of the Pacific 1998

References

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