Deep Extragalactic VLBI-Optical Survey (DEVOS)

I. Pilot MERLIN and VLBI observations

¹ Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary e-mail: mosoni@konkoly.hu
² FÖMI Satellite Geodetic Observatory, PO Box 585, 1592 Budapest, Hungary
³ Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo,The Netherlands
⁴ University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, UK
⁵ Department for Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA

Received: 19 May 2005
Accepted: 28 July 2005

Abstract

We present the results of the pilot observations of the Deep Extragalactic VLBI-Optical Survey (DEVOS). Our ultimate aim is to collect information on compact structures in a large sample of extragalactic radio sources (~10⁴ objects) up to two orders of magnitude fainter than those studied in typical imaging Very Long Baseline Interferometry (VLBI) surveys up until now. This would lead to an unprecedented data base for various astrophysical, astrometric and cosmological studies. The first global VLBI observations of the DEVOS programme were successfully conducted in May 2002. We selected sources without any spectral criterion from the Very Large Array (VLA) Faint Images of the Radio Sky at Twenty-centimeters (FIRST) catalogue, that are also detected with the Multi-Element Radio Linked Interferometer Network (MERLIN). The DEVOS pilot sample sources are in the area of the sky that is covered by the Sloan Digital Sky Survey (SDSS). We describe the sample selection and present high resolution 5-GHz radio images of the sources. Based on the results of this pilot study, we estimate the outcome of and the resources needed for a full-scale DEVOS project.