Observations of 44 extragalactic radio sources with the VLBA at 92 cm

A list of potential calibrators and targets for LOFAR and RadioAstron

¹ Joint Institute for VLBI in Europe (JIVE), Postbus 2, 7990 AA Dwingeloo, The Netherlands e-mail: [rampadarath;polatidis]@astron.nl
² Sterrewacht Leiden, Leiden University, Oort Building, Neils Bhorweg 2, 2333 CA, Leiden, The Netherlands
³ Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo, The Netherlands e-mail: garrett@astron.nl
⁴ Centre for Supercomputing, Swinburne University of Technology, Mail number H39, PO Box 218, Hawthorn, Victoria 3122, Australia

Received: 5 February 2009
Accepted: 14 March 2009

Abstract

Aims. We have analysed VLBA 92 cm archive data of 44 extragalactic sources in order to identify early targets and potential calibrator sources for the LOFAR radio telescope and the RadioAstron space VLBI mission. Some of these sources will also be suitable as “in-beam” calibrators, permitting deep, wide-field studies of other faint sources in the same field of view.

Methods. All publicly available VLBA 92 cm data observed between 1 January 2003 to December 31, 2006 have been analysed via an automatic pipeline, implemented within AIPS. The vast majority of the data are unpublished.

Results. The sample consists of 44 sources, 34 of which have been detected on at least one VLBA baseline. 30 sources have sufficient data to be successfully imaged. Most of the sources are compact, with a few showing extended structures. Of the 30 sources imaged, 13 are detected on the longest VLBA baselines (~9 Mλ), while all were detected on baselines greater than 2 Mλ (the maximum baseline of LOFAR including the current international baselines).