Letter to the Editor

High-resolution radio imaging of the most distant radio quasar SDSS J0836+0054

¹ FÖMI Satellite Geodetic Observatory, PO Box 585, 1592 Budapest, Hungary e-mail: frey@sgo.fomi.hu
² Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo, The Netherlands e-mail: [zparagi;lgurvits]@jive.nl
³ Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary e-mail: mosoni@konkoly.hu

Received: 11 March 2005
Accepted: 19 April 2005

Abstract

We observed SDSS J0836+0054, the most distant radio-loud quasar known at present () with the European Very Long Baseline Interferometry (VLBI) Network at the 5 GHz frequency on 2003 November 4. The source is compact at the milli-arcsecond (mas) angular scale with a flux density of 0.34 mJy. The observations with the Very Large Array (VLA) made on the consecutive day support a conclusion that the radio emission from SDSS J0836+0054 is essentially confined within the central 40 pc. Based on our phase-referenced VLBI observation, we obtained the astrometric position of the source accurate to ~2 mas.