  We describe a new program for determining photometric redshifts, dubbed EAZY.
The program is optimized for cases where spectroscopic redshifts are not
available, or only available for a biased subset of the galaxies. The code
combines features from various existing codes: it can fit linear combinations
of templates, it includes optional flux- and redshift-based priors, and its
user interface is modeled on the popular HYPERZ code. A novel feature is that
the default template set, as well as the default functional forms of the
priors, are not based on (usually highly biased) spectroscopic samples, but on
semi-analytical models. Furthermore, template mismatch is addressed by a novel
rest-frame template error function. This function gives different wavelength
regions different weights, and ensures that the formal redshift uncertainties
are realistic. We introduce a redshift quality parameter, Q_z, that provides a
robust estimate of the reliability of the photometric redshift estimate.
Despite the fact that EAZY is not "trained" on spectroscopic samples, the code
(with default parameters) performs very well on existing public datasets. For
K-selected samples in CDF-South and other deep fields we find a 1-sigma scatter
in dz/(1+z) of 0.034, and we provide updated photometric redshift catalogs for
the FIRES, MUSYC, and FIREWORKS surveys.
