The ATESP radio survey

III. Source counts

¹ Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40126 Bologna, Italy
² Istituto di Radioastronomia, CNR, Via Gobetti 101, 40129 Bologna, Italy
³ Dipartimento di Fisica, Università di Bologna, Via Irnerio 46, 40126 Bologna, Italy
⁴ Osservatorio Astronomico di Bologna, Via Ranzani 1, 40126 Bologna, Italy
⁵ Australia Telescope National Facility, CSIRO, PO Box 76, Epping NSW2121, Australia

Corresponding author: I. Prandoni, prandoni@ira.bo.cnr.it

Received: 4 August 2000
Accepted: 16 October 2000

Abstract

This paper is part of a series reporting the results of the ATESP radio survey obtained at 1.4 GHz with the Australia Telescope Compact Array. The survey consists of 16 radio mosaics with ∼ resolution and uniform sensitivity ( noise level ∼79 μJy) over the whole area of the ESO Slice Project redshift survey (∼26 sq. degr. at ). The ATESP survey has produced a catalogue of 2960 radio sources down to a flux limit () of ∼0.5 mJy. In this Paper we present the 1.4 GHz relation derived from the ATESP radio source catalogue. The possible causes of incompleteness at the faint end of the source counts are extensively discussed and their effects are quantified and corrected for. The ATESP counts are consistent with others reported in the literature, even though some significant discrepancies are present at low fluxes (below a few mJy). We investigate whether such discrepancies may be explained in terms of field-to-field anisotropies, considering the fact that all the existing sub-mJy surveys cover small areas of sky (from a fraction of square degree to a few square degrees). We stress that the ATESP survey, covering 26 sq. degr., provides the best determination of source counts available today in the flux range mJy.