Phase-reference mapping of a weak-cored double-lobed source in the 1636+473 system using MERLIN and Global VLBI

DOI: 
Publication date: 
01/01/1999
Main author: 
Rioja M.J.
IAA authors: 
Alberdi, A.
Authors: 
Rioja M.J., Porcas R.W., Garrington S., Alberdi A., Saikia D.J.
Journal: 
New Astronomy Reviews
Publication type: 
Article
Volume: 
43
Pages: 
593-597
Number: 
Abstract: 
We present maps and astrometric results from first epoch, simultaneous MERLIN and Global VLBI observations of the very weak core of a double-lobed radio source, using as reference the bright, compact, flat-spectrum quasar 1636+473 A, 20 arcsec away. The observations were made in May 1995 at 5 GHz. The phase-referenced VLBI map of the weak core, of resolution 1.5 mas, contains a high percentage of the core flux density seen in the MERLIN map. Further hybrid mapping iterations reveal a faint, one-sided core extension on the same side as the MERLIN jet. We explore the effect of both temporal and other coherence losses on the phase-reference map. We relate our results to the structural asymmetry in weak AGN cores within the context of unification models.
Database: 
SCOPUS
Keywords: 
95.10.Jk; 95.75.Kk; 98.54.Aj; 98.54.Gr; Astrometry; Galaxies: active; Galaxies: jets; Methods: data analysis; Quasars: general; Techniques: interferometry