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Astron. Astrophys. 325, 383-390

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Results from a decade-long VLBI astrometric monitoring
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 FORMULA 3.6 cm and FORMULA 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