Photometric redshifts and K-corrections for Sloan Digital Sky Survey
  Seven Data Release
  We present a catalogue of galaxy photometric redshifts and k-corrections for
the Sloan Digital Sky Survey Seven Data Release (SDSS-DR7), available on the
World Wide Web. The photometric redshifts were estimated with an artificial
neural network using five ugriz bands, concentration indices and Petrosian
radii in the g and r bands. We have explored our redshift estimates with
different training set concluding that the best choice to improve redshift
accuracy comprises the Main Galaxies Sample (MGS), the Luminous Red Galaxies,
and galaxies of active galactic nuclei covering the redshift range 0<z<0.3. For
the MGS, the photometric redshift estimates agree with the spectroscopic values
within rms=0.0227. The derived distribution of photometric redshifts in the
range 0<zphot<0.6 agrees well with the model predictions. k-corrections were
derived by calibration of the k-correct-v4.2 code results for the MGS with the
reference frame (z=0.1) (g-r) colours. We adopt a linear dependence of k
corrections on redshift and (g-r) colours that provide suitable distributions
of luminosity and colours for galaxies up to redshift zphot=0.6 comparable to
the results in the literature. Thus, our k-correction estimate procedure is a
powerful, low computational time algorithm capable of reproducing suitable
results that can be used for testing galaxy properties at intermediate
redshifts using the large SDSS database.
