Description
As part of the Data Release 5 of the Sloan Digital Sky Survey we have created a catalog of photometric redshifts and estimated absolute magnitudes, restframe colors, K-corrections and spectral types. This set of photometric redshift has been obtained with the template fitting method.
The template fitting approach simply compares the expected colors of a galaxy (derived from template spectral energy distributions) with those observed for an individual galaxy. The standard scenario for template fitting is to take a small number of spectral templates T (e.g., E, Sbc, Scd, and Irr galaxies) and choose the best fit by optimizing the likelihood of the fit as a function of redshift, type, and luminosity p(z, T, L). Variations on this approach have been developed in the last few decades, including ones that use a continuous distribution of spectral templates, enabling the error function in redshift and type to be well defined.
Since a representative set of photometrically calibrated spectra in the full wavelength range of the filters is not easy to obtain, we have used the empirical templates of Coleman Weedman and Wu extended with spectral synthesis models. These templates were adjusted to fit the calibrations (see Budavari et al. AJ 120 1588 (2000)).
For more detailed information see Csabai et al. AJ 125 580 (2003) and references therein.
The tables are available for the collaboration at CasJobs. Use context DR5QA and table PhotoZ.
Istvan Csabai
Norbert Purger
Tamas Budavari
Zsuzsa Gyory
Alex Szalay
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