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Multi-color classification in the calar alto deep imaging survey

Wolf, C. and Meisenheimer, K. and Röser, H.-J. and Beckwith, S. V. W. and Chaffee, F. H.,Jr. and Friedman, J. and Hippelein, H. and Huang, J.-S. and Kümmel, M. and von Kuhlmann, B. and Maier, C. and Phleps, S. and Rix, H.-W. and Thommes, E. and Thompson, D. (2001) Multi-color classification in the calar alto deep imaging survey. Astronomy & Astrophysics, 365 (3). pp. 681-698. ISSN 0004-6361. doi:10.1051/0004-6361:20000064.

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We use a multi-color classification method introduced by Wolf et al. ([CITE]) to reliably identify stars, galaxies and quasars in the up to 16-dimensional color space provided by the filter set of the Calar Alto Deep Imaging Survey (CADIS). The samples of stars, galaxies and quasars obtained this way have been used for dedicated studies which are published in separate papers. The classification is good enough to detect quasars rather completely and efficiently without confirmative spectroscopy. The multi-color redshifts are accurate enough for most statistical applications, e.g. evolutionary studies of the galaxy luminosity function. Also, the separation between stars and galaxies reaches deeper than with morphological criteria, so that studies of the stellar population can be extended to fainter levels. We characterize the dataset presently available on the CADIS 1 h-, 9 h- and 16 h-fields. Using Monte-Carlo simulations we model the classification performance expected for CADIS. We present a summary of the classification results on the CADIS database and discuss unclassified objects. More than 99% of the whole catalog sample at R < 22 (more than 95% at R < 23) are successfully classified matching the expectations derived from the simulations. A small number of peculiar objects challenging the classification is discussed in detail. Spectroscopic observations are used to check the reliability of the multi-color classification (6 mistakes among 151 objects with R < 24). From these, we also determine the accuracy of the multi-color redshifts which are rather good for galaxies (σ_z ≈ 0.03) and useful for quasars. We find that the classification performance derived from the simulations compares well with results from the real survey. Finally, we locate areas for potential improvement of the classification.

Item Type:Article
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URLURL TypeDescription
Wolf, C.0000-0002-4569-016X
Rix, H.-W.0000-0003-4996-9069
Additional Information:© ESO 2001. Received: 20 July 2000. Accepted: 24 October 2000. The authors thank H.-M. Adorf for helpful discussion about classification methods and their fine-tuning. We also thank the Calar Alto staff for their help and support during many observing runs at the observatory, especially Francisco Prada for observation and reduction of some bright galaxy spectra. We thank D. Calzetti for kindly making available the galaxy templates in digital form. This work was supported by the DFG (Sonderforschungsbereich 439).
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)Sonderforschungsbereich 439
Subject Keywords:methods: data analysis-- methods: statistical - techniques: photometric - surveys
Issue or Number:3
Record Number:CaltechAUTHORS:20180306-111804723
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Official Citation:Multi-color classification in the calar alto deep imaging survey C. Wolf, K. Meisenheimer, H.-J. Röser, S. V. W. Beckwith, F. H. Chaffee, J. Fried, H. Hippelein, J.-S. Huang, M. Kümmel, B. von Kuhlmann, C. Maier, S. Phleps, H.-W. Rix, E. Thommes and D. Thompson A&A, 365 3 (2001) 681-698 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85137
Deposited By: Ruth Sustaita
Deposited On:06 Mar 2018 21:58
Last Modified:15 Nov 2021 20:25

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