The VIRMOS deep imaging survey

IV. Near-infrared observations

¹ INAF – Osservatorio Astronomico di Brera, Via Brera 28, Milan, Italy e-mail: iovino@brera.mi.astro.it
² Institut d'Astrophysique de Paris, UMR 7095, 98 bis Bvd Arago, 75014 Paris, France
³ Observatoire de Paris, LERMA, 61 Avenue de l'Observatoire, 75014 Paris, France
⁴ IASF-INAF, via Bassini 15, 20133 Milano, Italy
⁵ Laboratoire d'Astropysique de Marseile, UMR 6110 CNRS-Université de Provence, BP 8, 13376 Marseille Cedex 12, France
⁶ INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁷ INAF-Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy
⁸ IRA-INAF – Via Gobetti 101, 40129 Bologna, Italy
⁹ Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (UMR 5572), 14 avenue E. Belin, 31400 Toulouse, France
¹⁰ Università di Bologna, Dipartimento di Astronomia, Via Ranzani 1, 40127 Bologna, Italy
¹¹ Max Planck Institut fur Astrophysik, 85741 Garching, Germany
¹² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei Munchen, Germany
¹³ Universitá di Milano-Bicocca, Dipartimento di Fisica, Piazza delle Scienze 3, 20126 Milano, Italy

Received: 4 March 2005
Accepted: 20 July 2005

Abstract

In this paper we present a new deep, wide-field near-infrared imaging survey. Our J- and K-band observations in four separate fields (0226-04, 2217+00, 1003+02, 1400+05) complement optical BVRI, ultraviolet and spectroscopic observations undertaken as part of the VIMOS-VLT deep survey (VVDS). In total, our survey spans ~. Our catalogues are reliable in all fields to at least and (defined as the magnitude where object contamination is less than 10% and completeness greater than 90%).
Taken together these four fields represents a unique combination of depth, wavelength coverage and area. Most importantly, our survey regions span a broad range of right ascension and declination which allow us to make a robust estimate of the effects of cosmic variance. We describe the complete data reduction process from raw observations to the construction of source lists and outline a comprehensive series of tests carried out to characterise the reliability of the final catalogues. From simulations we determine the completeness function of each final stacked image, and estimate the fraction of spurious sources in each magnitude bin. We compare the statistical properties of our catalogues with literature compilations. We find that our J- and K-selected galaxy counts are in good agreement with previously published works, as are our versus K colour–magnitude diagrams. Stellar number counts extracted from our fields are consistent with a synthetic model of our galaxy. Using the location of the stellar locus in colour-magnitude space and the measured field-to-field variation in galaxy number counts we demonstrate that the absolute accuracy of our photometric calibration is at the level or better. Finally, an investigation of the angular clustering of K-selected extended sources in our survey displays the expected scaling behaviour with limiting magnitude, with amplitudes in each magnitude bin in broad agreement with literature values. 
In summary, these catalogues will be an excellent tool to investigate the properties of near-infrared selected galaxies, and such investigations will be the subject of several articles currently in preparation.