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A&A Supplement Ser., Vol. 124, July 1997, 163-182

Received 22 August, 1995; accepted 18 October, 1996

The ESO-Sculptor faint galaxy redshift survey: The photometric sample

S. Arnouts tex2html_wrap2251 - V. de Lapparent tex2html_wrap2253 - G. Mathez tex2html_wrap2255 - A. Mazure tex2html_wrap2257 - Y. Mellier tex2html_wrap2259 - E. Bertin tex2html_wrap2261 - A. Kruszewski tex2html_wrap2263

Send offprint request: S. Arnouts

tex2html_wrap2265  CNRS, Institut d'Astrophysique de Paris, 98 bis, Boulevard Arago, F-75014 Paris, France
tex2html_wrap2267  European Southern Observatory, Casilla 19001, Santiago, Chile
tex2html_wrap2269  Observatoire Midi-Pyrénées, Laboratoire d'Astrophysique de Toulouse, URA 285, 14, avenue Edouard Belin, F-31400 Toulouse, France
tex2html_wrap2271  Laboratoire d'Astronomie Spatiale, B.P. No. 8, F-13376 Marseille Cedex 12, France
tex2html_wrap2273  Warsaw University Observatory, Al. Ujazdowskie 4, PL-00-478 Warsaw, Poland


We present the photometric sample of a faint galaxy survey carried out in the southern hemisphere, using CCD imaging at the 3.60 m and NTT-3.5 m telescopes at La Silla (ESO). The survey area is a continuous strip of tex2html_wrap_inline2201 located at high galactic latitude (tex2html_wrap_inline2203) in the Sculptor constellation. The photometric survey provides total magnitudes in the bands B, V (Johnson) and R (Cousins) to limiting magnitudes of 24.5, 24.0, 23.5 respectively. To these limits, the catalog contains about 9500, 12150, 13000 galaxies in B, V, R bands respectively and is the first large digital multi-colour photometric catalog at this depth. This photometric survey also provides the entry catalog for a fully-sampled redshift survey of tex2html_wrap_inline2217 700 galaxies with tex2html_wrap_inline2219 (Bellanger et al. 1995a).
In this paper, we describe the photometric observations and the steps used in the data reduction. The analysis of objects and the star-galaxy separation with a neural network are performed using SExtractor, a new photometric software developed by E. Bertin (1996). By application of SExtractor to simulated frames and comparison of multiple measurements, we estimate that the photometric accuracy of our catalog is tex2html_wrap_inline2221 for tex2html_wrap_inline2223. Then, we use a method to obtain a homogeneous photometric scale over the whole survey using the overlapping regions of neighbouring CCDs. The differential galaxy number counts in B, V, R are in good agreement with previously published CCD studies and confirm the evidence for significant evolution at faint magnitudes as compared to a standard non evolving model (by factors 3.6, 2.6, 2.1). The galaxy colour distributions B-R, B-V of our sample show a blueing trend of tex2html_wrap_inline2235 between 21 < R < 23.5 in contrast to the V-R colour distribution where no significant evolution is observed.

keywords: galaxies: redshifts; photometry -- cosmology: observations

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