An Automatic System for Photometric Redshift Estimation Based on Sky Survey Data

With the large-scale multicolor photometry and fiber-based spectroscopy projects carried out, millions of uniform samples are available to the astronomers'. Based oil this situation, we have developed all automatic system to estimate photometric redshifts for both galaxies and quasars. In this paper we give an exhaustive introduction of the system. We first describe a series of methods integrated in this system, such as template fitting, color-magnitude- redshift; relation, polynomial regression, support vector machines and kernel regression. The merits and demerits of these approaches have been indicated. Therefore, users call choose some suitable algorithm to estimate photometric redshifts according to data characteristics and science requirements. Then, we present. a case study to illustrate how the system works. In order to build a more robust system of increasing the accuracy and speed of photometric redshift, estimation, we pay special attention to algorithm choice and data preparation. From the user's viewpoint, an easy used interface will be provided. Finally, we point out the promising techniques of measuring photometric redshifts and the application prospects of this system. In the future, the system will become an essential tool For automatedly determining photometric redshifts in the study of the large-scale structure of the Universe and the formation and evolution of galaxies.