Polycyclic Aromatic Hydrocarbon emission in Spitzer/IRS maps I: Catalog
  and simple diagnostics
  We present a sample of resolved galactic HII regions and photodissociation
regions (PDRs) observed with the Spitzer infrared spectrograph (IRS) in
spectral mapping mode between the wavelengths of 5--15 $\mu$m. For each object
we have spectral maps at a spatial resolution of $\sim$4" in which we have
measured all of the mid-infrared emission and absorption features. These
include the PAH emission bands, primarily at 6.2, 7.7, 8.6, 11.2 and 12.7
$\mu$m, as well as the spectral emission lines of neon and sulfur and the
absorption band caused by silicate dust at around 9.8 $\mu$m. In this work we
describe the data in detail, including the data reduction and measurement
strategies, and subsequently present the PAH emission band intensity
correlations for each of the objects and the sample as a whole. We find that
there are distinct differences between the sources in the sample, with two main
groups, the first comprising the HII regions and the second the reflection
nebulae (RNe). Three sources, the reflection nebula NGC~7023, the Horsehead
nebula PDR (an interface between the HII region IC~434 and the Orion B
molecular cloud) and M 17, resist this categorization, with the Horsehead PDR
points mimicking the RNe and the NGC~7023 fluxes displaying unique bifurcated
appearance in our correlation plots. These discrepancies seem to be due to the
very low radiation field experienced by the Horsehead PDR and the very clean
separation between the PDR environment and a diffuse environment in the
NGC~7023 observations.
