P-MaNGA: Full spectral fitting and stellar population maps from
  prototype observations
  MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-year
SDSS-IV survey that will obtain resolved spectroscopy from 3600 $\AA$ to 10300
$\AA$ for a representative sample of over 10,000 nearby galaxies. In this
paper, we derive spatially resolved stellar population properties and radial
gradients by performing full spectral fitting of observed galaxy spectra from
P-MaNGA, a prototype of the MaNGA instrument. These data include spectra for
eighteen galaxies, covering a large range of morphological type. We derive age,
metallicity, dust and stellar mass maps, and their radial gradients, using high
spectral-resolution stellar population models, and assess the impact of varying
the stellar library input to the models. We introduce a method to determine
dust extinction which is able to give smooth stellar mass maps even in cases of
high and spatially non-uniform dust attenuation.
  With the spectral fitting we produce detailed maps of stellar population
properties which allow us to identify galactic features among this diverse
sample such as spiral structure, smooth radial profiles with little azimuthal
structure in spheroidal galaxies, and spatially distinct galaxy sub-components.
In agreement with the literature, we find the gradients for galaxies identified
as early-type to be on average flat in age, and negative (- 0.15 dex / R$_e$ )
in metallicity, whereas the gradients for late-type galaxies are on average
negative in age (- 0.39 dex / R$_e$ ) and flat in metallicity. We demonstrate
how different levels of data quality change the precision with which radial
gradients can be measured. We show how this analysis, extended to the large
numbers of MaNGA galaxies, will have the potential to shed light on galaxy
structure and evolution.
