Classifying Objects by Medium-Band Observations
- a spectrophotometric 17-filter survey -

The public COMBO-17 CDFS data:

12 September 2008 -- changes redshifts and rest-frame colours

We present the COMBO-17 object catalogue on the Chandra Deep Field South for public use, covering a field which is 31.5'x 30' 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 10000 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 M_B=-21.7. Their photometric redshifts are accurate to roughly 5000 km/sec. Galaxy redshifts are accurate to 1% in dz/(1+z) at R<21. They degrade in quality for progressively fainter galaxies, reaching accuracies of 2% for galaxies with R~22 and of 10% for galaxies with R>24. The selection of stars is complete to R~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>24.

The reference paper
with all details
(Wolf et al., 2004, A&A, 421, 913)

The update paper
(Wolf et al., 2008, A&A Research Note,submitted)

The dataset (2008 update):

The ReadMe file for the ASCII catalogue in CDS format

The ASCII catalogue (60 MB) and The FITS catalogue (33 MB)

The U-band image The B-band image The V-band image The R-band image The I-band image

Back to COMBO-17 index page

Last update September 12, 2008, CW