  We present MASSCLEAN, a new, sophisticated and robust stellar cluster image
and photometry simulation package. This visualization tool is able to create
color-magnitude diagrams and standard FITS images in any of the traditional
optical and near-infrared bands based on cluster characteristics input by the
user, including but not limited to distance, age, mass, radius and extinction.
At the limit of very distant, unresolved clusters, we have checked the
integrated colors created in MASSCLEAN against those from other simple stellar
population models with consistent results. We have also tested models which
provide a reasonable estimate of the field star contamination in images and
color-magnitude diagrams. We demonstrate the package by simulating images and
color-magnitude diagrams of well known massive Milky Way clusters and compare
their appearance to real data. Because the algorithm populates the cluster with
a discrete number of tenable stars, it can be used as part of a Monte Carlo
Method to derive the pr obabilistic range of characteristics (integrated
colors, for example) consistent with a given cluster mass and age. Our
simulation package is available for download and will run on any standard
desktop running UNIX/Linux. Full documentation on installation and its use is
also available. Finally, a web-based version of MASSCLEAN which can be
immediately used and is sufficiently adaptable for most applications is
available through a web interface.
