The O- and B-Type Stellar Population in W3: Beyond the High-Density
  Layer
  We present the first results from our survey of the star-forming complex W3,
combining VRI photometry with multiobject spectroscopy to identify and
characterize the high-mass stellar population across the region. With 79 new
spectral classifications, we bring the total number of
spectroscopically-confirmed O- and B-type stars in W3 to 105. We find that the
high-mass slope of the mass function in W3 is consistent with a Salpeter IMF,
and that the extinction toward the region is best characterized by an Rv of
approximately 3.6. B-type stars are found to be more widely dispersed across
the W3 giant molecular cloud (GMC) than previously realized: they are not
confined to the high-density layer (HDL) created by the expansion of the
neighboring W4 HII region into the GMC. This broader B-type population suggests
that star formation in W3 began spontaneously up to 8--10 Myr ago, although at
a lower level than the more recent star formation episodes in the HDL. In
addition, we describe a method of optimizing sky subtraction for fiber spectra
in regions of strong and spatially-variable nebular emission.
