VLBI Astrometry of the Ultra-Compact Nucleus of M81
- 1 January 1998
- journal article
- research article
- Published by Cambridge University Press (CUP) in International Astronomical Union Colloquium
- Vol. 164, 203-204
- https://doi.org/10.1017/s0252921100045218
Abstract
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.Keywords
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