Toward More Precise Photometric Redshifts: Calibration via CCD Photometry

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Abstract
We present the initial results from a deep, multiband photometric survey of selected high Galactic latitude redshift fields. Previous work using the photographic data of Koo and Kron demonstrated that the distribution of galaxies in the multidimensional flux space U, B, R, and I is nearly planar. The position of a galaxy within this plane is determined by its redshift, luminosity, and spectral type (Connolly et al. 1995). Using recently acquired deep CCD photometry in existing, published redshift fields, we have redetermined the distribution of galaxies in this four-dimensional magnitude space. Furthermore, from our CCD photometry and the published redshifts, we have quantified the photometric-redshift relation within the standard AB magnitude system. This empirical relation has a measured dispersion of σz ≈ 0.02 for z < 0.4. With this work we are reaching the asymptotic intrinsic dispersions (σz ≈ 0.016 for z < 0.4) that were predicted from simulated distributions of galaxy colors. This result will prove useful in providing estimated redshifts for large photometric surveys, as well as improve the sampling of specific redshift regions for spectroscopic surveys through the use of an estimated redshift selection criteria.
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