Calibration update of the COMBO-17 CDFS catalogue

TL;DR

This paper updates the photometric calibration of the COMBO-17 catalogue in the CDFS, improving the accuracy of photometric redshifts and discussing implications for galaxy colours at low redshift.

Contribution

The paper provides a recalibration of the COMBO-17 catalogue, aligning it with other surveys and enhancing photometric redshift precision.

Findings

Photometric redshifts now have <0.01 rms accuracy for bright galaxies and QSOs.

Calibration alignment reduces biases in galaxy colour measurements.

Photometric redshift errors increase with fainter magnitudes, reaching 0.035 at R~23.5.

Abstract

We present an update to the photometric calibration of the COMBO-17 catalogue on the Extended Chandra Deep Field South, which is now consistent with the GaBoDS and MUSYC catalogues. As a result, photometric redshifts become slightly more accurate, with <0.01 rms and little bias in the delta_z/(1+z) of galaxies with R<21 and of QSOs with R<24. With increasing photon noise the rms of galaxies reaches 0.02 for R<23 and 0.035 at R~23.5. Consequences for the rest-frame colours of galaxies at z<1 are discussed.