EDP Sciences
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Volume 421, Number 3, July III 2004
Page(s) 913 - 936
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20040525

A&A 421, 913-936 (2004)
DOI: 10.1051/0004-6361:20040525

A catalogue of the Chandra Deep Field South with multi-colour classification and photometric redshifts from COMBO-17

C. Wolf1, K. Meisenheimer2, M. Kleinheinrich2, A. Borch2, S. Dye3, M. Gray4, L. Wisotzki5, E. F. Bell2, H.-W. Rix2, A. Cimatti6, G. Hasinger7 and G. Szokoly7

1  Department of Physics, Denys Wilkinson Bldg., University of Oxford, Keble Road, Oxford, OX1 3RH, UK
2  Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
3  Astrophysics Group, Blackett Lab, Imperial College, Prince Consort Road, London, UK
4  School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
5  Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
6  Istituto Nazionale di Astrofisica (INAF), Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
7  Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany

(Received 25 March 2004 / Accepted 9 April 2004)

We present the COMBO-17 object catalogue of the Chandra Deep Field South for public use, covering a field which is $31\farcm5$  $\times$ $30\arcmin$ in size. This catalogue lists astrometry, photometry in 17 passbands from 350 to 930 nm, and ground-based morphological data for 63 501 objects. The catalogue also contains multi-colour classification into the categories Star, Galaxy and Quasar as well as photometric redshifts. We include restframe luminosities in Johnson, SDSS and Bessell passbands and estimated errors. The redshifts are most reliable at R<24, where the sample contains approximately 100 quasars, 1000 stars and 10 000 galaxies. We use nearly 1000 spectroscopically identified objects in conjunction with detailed simulations to characterize the performance of COMBO-17. We show that the selection of quasars, more generally type-1 AGN, is nearly complete and minimally contaminated at z=[0.5,5] for luminosities above MB = -21.7 . Their photometric redshifts are accurate to roughly 5000 km s -1. Galaxy redshifts are accurate to 1% in  $\delta_z/(1+z)$ at  R<21. They degrade in quality for progressively fainter galaxies, reaching accuracies of 2% for galaxies with $R \sim 22$ and of 10% for galaxies with R>24. The selection of stars is complete to $R \sim 23$, and deeper for M stars. We also present an updated discussion of our classification technique with maps of survey completeness, and discuss possible failures of the statistical classification in the faint regime at  $R\ga 24$.

Key words: catalogs -- surveys -- techniques: photometric -- methods: observational -- galaxies: general

Offprint request: C. Wolf, cwolf@astro.ox.ac.uk

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