  Cosmic-ray observatories necessarily rely on Monte Carlo simulations for
their design, calibration and analysis of their data. Detailed simulations are
very demanding computationally. We present a python-based package called
ShowerModel to model cosmic-ray showers, their light production and their
detection by an array of telescopes. It is based on parameterizations of both
Cherenkov and fluorescence emission in cosmic-ray induced air showers. The
package permits the modelling of fluorescence telescopes, imaging air Cherenkov
telescopes, wide-angle Cherenkov detectors or any hybrid design.
  ShowerModel was conceived as a tool to speed up calculations that do not
require a full simulation or that may serve to complement complex Monte Carlo
studies and data analyses (e.g., as a cross-check). It can also be used for
educational purposes.
