The Parkes quarter-Jansky flat-spectrum sample

Abstract

Abstract. We present a new sample of quarter-Jansky flat-spectrum radio sources selected to search for highredshift quasars and to study the evolution of the flat-spectrum quasar population. The sample comprises 878 radio sources selected from the Parkes catalogues with spectral indices α 5 GHz 2.7 GHz ≥ −0.4 where Sν ∝ ν α . The sample covers all right ascensions and the declination range from −80.• 0 to +2.• 5, excluding low galactic latitudes (| b |< 10• ) and the Magellanic Cloud regions. We have obtained improved radio source positions, firstly to reconfirm the majority of the existing identifications, and secondly, using digitized sky-survey data and deep B, Gunn-i and Gunn-z CCD-imaging, to find optical identifications for 223 previously-unidentified sources. We present the final catalogue of 878 flat-spectrum sources: 827 are compact radio sources identified with galaxies, quasars and BL Lac objects, 38 have either extended radio structure or are identified with Galactic objects (PN, HII or non-compact radio source), 4 are obscured by Galactic stars, and 9 (1 per cent of the total sample) remain unidentified.

The Parkes quarter-Jansky flat-spectrum sample

“…As a result of the spectroscopic observations described above, the Parkes quarter-Jansky flat-spectrum sample has highly complete redshift information (see Jackson et al 2002). In summary, there are 677 objects classified as quasars or BLs in the original sample of 878.…”

“…The "conf" column gives a level of confidence in the redshift (0 = no lines for redshift determination, 1 = secure redshift, 2 = single line or weak lines). The Class column gives the classification, reproduced from Jackson et al (2002). These classifications are based on both the spectrum and images of the source and their meanings are as follows: Q =confirmed quasar by spectroscopy or UVX photometry; BL = spectroscopically-confirmed BL Lac object; G = Galaxy with morphological or spectroscopic confirmation; NCS = Non-compact radio source (the source is either a steep-spectrum or extended radio source).…”

“…We have defined a sample of flat-spectrum radio sources from the PKSCAT90 catalogue (Wright & Otrupeck 1990) as described in Jackson et al (2002). The sample of 878 sources was selected based on the following criteria: α 5.0 GHz 2.7 GHz > −0.4, where S ∝ ν α , −80 • < δ < +2.5 • , |b| ≥ 10 • .…”

“…The sample of 878 sources was selected based on the following criteria: α 5.0 GHz 2.7 GHz > −0.4, where S ∝ ν α , −80 • < δ < +2.5 • , |b| ≥ 10 • . The optical identification procedure, including new radio positions that were obtained as part of this study, is described in Jackson et al (2002) and a full set of finding charts is given there. The majority of identifications were made using COSMOS scans of UKST B J plates, and CCD identifications were obtained for those sources not identified on the plates.…”

“…The first paper (Paper 1, Jackson et al 2002) set out the sample, discussing its selection and the identification and reconfirmation programme to determine the optical counterparts to the radio sources. This paper, Paper 2, presents new spectroscopic observations and redshift determinations.…”