Improved Photometric Redshifts via Enhanced Estimates of System
  Response, Galaxy Templates, and Magnitude Priors
  Wide, deep photometric surveys require robust photometric redshift estimates
(photo-z's) for studies of large-scale structure. These estimates depend
critically on accurate photometry. We describe the improvements to the
photometric calibration and the photo-z estimates in the Deep Lens Survey (DLS)
from correcting three of the inputs to the photo-z calculation: the system
response as a function of wavelength, the spectral energy distribution
templates, and template prior probabilities as a function of magnitude. We
model the system response with a physical model of the MOSAIC camera's CCD,
which corrects a 0.1 magnitude discrepancy in the colours of type M2 and later
stars relative to the SDSS z-band photometry. We provide our estimated z-band
response function for the use of other surveys that used MOSAIC before its
recent detector upgrade. The improved throughput curve, template set, and
Bayesian prior lead to a 20 per cent reduction in photo-z scatter and a
reduction of the bias by a factor of more than two. This paper serves as both a
photo-z data release description for DLS and a guide for testing the quality of
photometry and resulting photo-z's generally.
