Absolute kinematics of radio source components in the complete S5 polar cap sample

III. First wide-field high-precision astrometry at 15.4 GHz

¹ Departament d'Astronomia i Astrofísica, Universitat de València, C/ Dr. Moliner 50, 46100 Burjassot, València, Spain e-mail: I.Marti-Vidal@uv.es
² Instituto de Astrofísica de Andalucía, C/ Camino bajo de Huétor 50, 18008 Granada, Spain
³ Max-Planck-Institut für Radioastronomie, Postfach 2024, 53010 Bonn, Germany

Received: 12 June 2007
Accepted: 17 September 2007

Abstract

We report on the first wide-field, high-precision astrometric analysis of the 13 extragalactic radio sources of the complete S5 polar cap sample at 15.4 GHz. We describe new algorithms developed to enable the use of differenced phase delays in wide-field astrometric observations and discuss the impact of using differenced phase delays on the precision of the wide-field astrometric analysis. From this global fit, we obtained estimates of the relative source positions with precisions ranging from 14 to 200 μas at 15.4 GHz, depending on the angular separation of the sources (from ~1.6 to ~20.8 degrees). These precisions are ~10 times higher than the achievable precisions using the phase-reference mapping technique.