Discovery of radio-loud quasars with redshifts above 4 from the PMN sample ^*,**

¹ Department of Physics, University of Oxford, Nuclear & Astrophysics Laboratory, Keble Road, Oxford OX1 3RH, UK e-mail: imh@astro.ox.ac.uk
² Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
³ European Southern Observatory, Karl Schwarzschild Straße 2, 85748 Garching b. München, Germany
⁴ Institute for Astronomy, Royal Observatory, Edinburgh, EH9 3HJ, UK

Corresponding author: I. M. Hook, ihook@gemini.edu

Received: 5 February 2002
Accepted: 11 June 2002

Abstract

We present results of a new, large survey for high-redshift radio-loud quasars, which targets quasars with . The survey is based on the PMN and NVSS radio surveys, optically identified using digitised UKST B, R and I plates. Six new flat-spectrum QSOs have been discovered, and one previously known QSO rediscovered, based on their red optical colours. The QSOs discovered in this survey are bright in both radio and optical bands; in particular PMN J1451-1512 (, , ) and PMN J0324-2918 (, ) are very luminous. PMN J1451-1512 at is also now the most distant radio-selected quasar. In addition, 9 new quasars with were discovered during the survey. We present spectra and finding charts for the new quasars. We also derive a surface density of for flat-spectrum QSOs with  mJy and  mag.