  The "TNOs are Cool!: A survey of the trans-Neptunian region" is a Herschel
Open Time Key Program that aims to characterize planetary bodies at the
outskirts of the Solar System using PACS and SPIRE data, mostly taken as
scan-maps. In this paper we summarize our PACS data reduction scheme that uses
a modified version of the standard pipeline for basic data reduction, optimized
for faint, moving targets. Due to the low flux density of our targets the
observations are confusion noise limited or at least often affected by bright
nearby background sources at 100 and 160\,$\mu$m. To overcome these problems we
developed techniques to characterize and eliminate the background at the
positions of our targets and a background matching technique to compensate for
pointing errors. We derive a variety of maps as science data products that are
used depending on the source flux and background levels and the scientific
purpose. Our techniques are also applicable to a wealth of other Herschel solar
system photometric observations, e.g. comets and near-Earth asteroids. The
principles of our observing strategies and reduction techniques for moving
targets will also be applicable for similar surveys of future infrared space
projects.
