Metallicities and ages of stellar populations at a high Galactic
  latitude field
  We present an analysis of $UBVRI$ data from the Selected Area SA 141. By
applying recalibrated methods of measuring ultraviolet excess (UVX), we
approximate abundances and absolute magnitudes for 368 stars over 1.3 square
degrees out to distances over 10 kpc. With the density distribution constrained
from our previous photometric parallax investigations and with sufficient
accounting for the metallicity bias in the UVX method, we are able to compare
the vertical abundance distribution to those measured in previous studies. We
find that the abundance distribution has an underlying uniform component
consistent with previous spectroscopic results that posit a monometallic thick
disk and halo with abundances of $[Fe/H]$ = $-$0.8 and $-$1.4, respectively.
However, there are a number of outlying data points that may indicate
contamination by more metal-rich halo streams. The absence of vertical
abundance gradients in the Galactic stellar populations and the possible
presence of interloping halo streams would be consistent with expectations from
merger models of Galaxy formation. We find that our UVX method has limited
sensitivity in exploring the metallicity distribution of the distant Galactic
halo, owing to the poor constraint on the $UBV$ properties of very metal-poor
stars. The derivation of metallicities from broadband $UBV$ photometry remains
fundamentally sound for the exploration of the halo but is in need of both
improved calibration and superior data.
