Spectrophotometry of the Huygens Region of the Orion Nebula, the
  Extended Orion Nebula, and M~43; Scattered Light Systematically Distorts
  Conditions Derived from Emission-Lines
  We report on medium resolution spectrophotometry of the Orion Nebula region,
including for the first time the Extended Orion Nebula and the nearby M~43. The
49 long slit observations were divided into 99 smaller samples, which have
allowed determinations of the amount of extinction, extinction corrected
\Hbeta\ surface brightness, electron temperatures (from [S~II], [N~II], and
[O~III]), and electron densities (from [S~II] and [Cl~III]) throughout much of
this complex region.
  We verify an earlier conclusion from a radio/optical study that beyond about
5\arcmin\ from \ori\ local emission begins to be contaminated by scattering of
light from the much brighter central Huygens Region of M~42 and this scattered
light component becomes dominant at large distances. This contamination means
that the derived properties for the outer regions are not accurate. From
comparison of the light from the dominant star in M~43 with the continuum of
that nebula (which is almost entirely scattered star light) it is determined
that scattered light is enhanced in the blue, which can lead to observed Balmer
line ratios that are theoretically impossible and erroneous electron
temperatures.
  This blue scattering of emission-lines is important even in the Huygens
Region because it means that at anything except very high spectroscopic
resolution the observed lines are a blend of the original and scattered light,
with shorter wavelength lines being artificially enhanced. This can lead to
over-estimates of the electron temperatures derived from the nebular and
auroral line ratios of forbidden lines. This phenomenon is probably applicable
to many other H~II regions.
