  Coronal holes are usually defined as dark structures as seen in the extreme
ultraviolet and X-ray spectrum which are generally associated with open
magnetic field. Deriving reliably the coronal hole boundary is of high
interest, as its area, underlying magnetic field, and other properties give
important hints towards high speed solar wind acceleration processes and on
compression regions arriving at Earth. In this study we present a new threshold
based extraction method that incorporates the intensity gradient along the
coronal hole boundary, which is implemented as a user-friendly SSWIDL GUI. The
Collection of Analysis Tools for Coronal Holes (CATCH) enables the user to
download data, perform guided coronal hole extraction and analyze the
underlying photospheric magnetic field. We use CATCH to analyze non-polar
coronal holes during the SDO-era, based on 193 {\AA} filtergrams taken by the
Atmospheric Imaging Assembly (AIA) and magnetograms taken by the Heliospheric
and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO).
Between 2010 and 2019 we investigate 707 coronal holes that are located close
to the central meridian. We find coronal holes distributed across latitudes of
about +/- 60 degree for which we derive sizes between 1.6 x 10 9 and 1.8 x 10
11 km^2 . The absolute value of the mean signed magnetic field strength tends
towards an average of 2.9 +/- 1.9 G. As far as the abundance and size of
coronal holes is concerned, we find no distinct trend towards the northern or
southern hemisphere. We find that variations in local and global conditions may
significantly change the threshold needed for reliable coronal hole extraction
and thus, we can highlight the importance of individually assessing and
extracting coronal holes.
