Astron. Astrophys. 325, 383-390
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Results from a decade-long VLBI astrometric
of the pair
of quasars 1038+528 A and B
M.J. Rioja1,2, J.M. Marcaide1,3, P. Elósegui1,4, and I.I. Shapiro4
1Instituto de Astrofísica de Andalucía
CSIC, Apartado 3004, E-18080 Granada, Spain
2Joint Institute for VLBI in Europe (JIVE), Postbus 2,
7990 AA Dwingeloo, The Netherlands
3Dpto. de Astronomía y Astrofísica,
Universitat de Valencia, E-46100 Burjassot, Valencia, Spain
4Harvard-Smithsonian Center for Astrophysics,
Cambridge, MA 02138, USA
Received 13 November 1996 / Accepted 6 March 1997
We present results from three epochs, spanning nearly a decade, of
VLBI monitoring of the angular
separation between the quasars 1038+528 A and B.
Our observations, made simultaneously at 3.6 cm
and 13 cm, achieve submilliarcsecond (submas) precision
in the measurement of the ~ 33'' separation between the two quasars.
We detected changes in this angular separation of nearly 0.2 mas.
These changes can be explained wholly, or mostly, by the motion of the
reference feature used in quasar B which appears to be a component in the
jet, separating from the core at a speed near c.
We also conclude that any proper motion of quasar A is
less than 10 µas yr-1. There is an intriguing hint of a "jitter"
in the position of the peak brightness of this quasar, but the signal-to-noise
ratio is too low for us to draw a firm conclusion.
Key words: astrometry and celestial mechanics: instrumentation: interferometers - astrometry - galaxies: quasars - radio continuum: galaxies
Send offprint requests to: M.J. Rioja (JIVE)
© European Southern Observatory (ESO) 1997