The Great Observatories Origins Deep Survey^*,**

VLT/ISAAC near-infrared imaging of the GOODS-South field

¹ European Organisation for Astronomical Research in the Southern Hemisphere (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany e-mail: jretzlaf@eso.org
² NOAO, 950 N. Cherry Avenue, Tucson, AZ 85719, USA
³ Canon Research Centre, rue Touche Lambert, 35510 Cesson Sévigné, France
⁴ Ministério da Ciência e Tecnologia – Observatório Nacional, Rua Gal. Jose Cristino 77, Sao Cristovao, Rio de Janeiro – RJ, Brasil
⁵ INAF - Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy
⁶ CEA Saclay, Haute-commissaire à l'Énergie Atomique, 91191 Gif-sur-Yvette, France

Received: 20 July 2009
Accepted: 7 December 2009

Abstract

Aims. We present the final public data release of the VLT/ISAAC near-infrared imaging survey in the GOODS-South field. The survey covers an area of 172.5, 159.6 and 173.1 arcmin in the J, H, and bands, respectively. For point sources total limiting magnitudes of J=25.0, H=24.5, and (, AB) are reached within 75% of the survey area. Thus these observations are significantly deeper than the previous EIS Deep Public Survey which covers the same region. The image quality is characterized by a point spread function ranging between 0.34´´ and 0.65´´ FWHM. The images are registered to a common astrometric grid defined by the GSC 2 with an accuracy of ~ RMS over the whole field. The overall photometric accuracy, including all systematic effects, adds up to 0.05 mag. The data are publicly available from the ESO science archive facility.

Methods. We describe the data reduction, the calibration, and the quality control process. The final data set is characterized in terms of astrometric and photometric properties, including the PSF and the curve of growth. We establish an empirical model for the sky background noise in order to quantify the variation of limiting depth and statistical photometric errors over the survey area. We define a catalog of -selected sources which contains photometry for 7079 objects. Differential aperture corrections were applied to the color measurements in order to avoid possible biases as a result of the variation of the PSF. We briefly discuss the resulting color distributions in the context of available redshift data. Furthermore, we estimate the completeness fraction and relative contamination due to spurious detections for source catalogs extracted from the survey data. For this purpose, an empirical study based on a deep image of the Hubble Ultra Deep Field is combined with extensive image simulations.

Results. With respect to previous deep near-infrared surveys, the surface density of faint galaxies has been established with unprecedented accuracy by virtue of the unique combination of depth and area of this survey. We derived galaxy number counts over eight magnitudes in flux up to J=25.25, H=25.0, (in the AB system). Very similar faint-end logarithmic slopes between 0.24 and 0.27 mag were measured in the three bands. We found no evidence for a significant change in the slope of the logarithmic galaxy number counts at the faint end.