OTELO survey: deep BVRI broad-band photometry of the Groth strip^*

I. Number counts and two-point correlation functions

¹ Instituto de Astrofísica de Canarias, 38205 La Laguna, Spain e-mail: jcn@iac.es
² Departamento de Astrofísica, Universidad de La Laguna, Spain
³ Instituto de Astrofísica de Andalucía-CSIC, Granada, Spain
⁴ Departamento de Astrofísica y CC. de la Atmósfera Universidad Complutense de Madrid, Madrid, Spain
⁵ Instituto de Física de Cantabria, Santander, Spain
⁶ Herschel Science Center, INSA/ESAC, Madrid, Spain
⁷ Instituto de Astronomía UNAM, México D.F, México

Received: 29 April 2008
Accepted: 8 July 2008

Abstract

Context. The Groth field is one of the sky regions that will be targeted by the OTELO (OSIRIS Tunable Filter Emission Line Object) survey in the optical 820 nm and 920 nm atmospheric windows. A complementary broad-band photometric catalogue of the field is essential for several purposes, in particular the inequivocal identification of sources, photometric redshift estimation, and population synthesis fitting.

Aims. We aim to describe the OTELO survey and present deep BVRI imaging data of the Groth field. Galaxy number counts, colour distributions and galaxy clustering are analysed.

Methods. BVRI deep images (>8 ks) were obtained with the Prime Focus Camera at the WHT (La Palma) and reduced with the IRAF package. The extraction and photometry of the sources was done with SExtractor software. We analysed the final catalogue to obtain galaxy number counts, as well as galaxy correlation functions as a function of I magnitude and colour. It is also compared with estimations from mock catalogues of the Virgo-Millenium consortium.

Results. We find excellent agreement between observed and mock data number counts. We also find evidence of galaxy clustering evolution and strong dependence of the angular correlation function on the observed colour. Our data favour a flattening of the clustering amplitude with median apparent magnitude. The good general agreement between our clustering analysis and the estimates from the mock data is remarkable.