  Coronal lines are a powerful, yet poorly understood, tool to identify and
characterize Active Galactic Nuclei (AGNs). There have been few large scale
surveys of coronal lines in the general galaxy population in the literature so
far. Using a novel pre-selection technique with a flux-to-RMS ratio $F$,
followed by Markov-Chain Monte Carlo (MCMC) fitting, we searched for the full
suite of 20 coronal lines in the optical spectra of almost 1 million galaxies
from the Sloan Digital Sky Survey (SDSS) Data Release 8. We present a catalog
of the emission line parameters for the resulting 258 galaxies with detections.
The Coronal Line Activity Spectroscopic Survey (CLASS) includes line
properties, host galaxy properties, and selection criteria for all galaxies in
which at least one line is detected. This comprehensive study reveals that a
significant fraction of coronal line activity is missed in past surveys based
on a more limited set of coronal lines; $\sim$60% of our sample do not display
the more widely surveyed [Fe X] $\lambda$6374. In addition, we discover a
strong correlation between coronal line and WISE W2 luminosities, suggesting
that the mid-infrared flux can be used to predict coronal line fluxes. For each
line we also provide a confidence level that the line is present, generated by
a novel neural network, trained on fully simulated data. We find that after
training the network to detect individual lines using 100,000 simulated
spectra, we achieve an overall true positive rate of 75.49% and a false
positive rate of only 3.96%.
