A Grid of YSO Models and a Data Fitter
          Thomas Robitaille, U. St Andrews
          Barbara Whitney, Space Science Institute
          Pia Denzmore, Rice U.
          Remy Indebetouw, U. Virginia
          Kenneth Wood, U. St Andrews
          Ed Churchwell, U. Wisconsin-Madison

          We have computed a grid of over 2000 2-D radiation transfer models of Young Stellar Objects (YSOs), and developed a tool that will fit photometric data with models from the grid. The fitter is capable of dealing with large datasets (thousands to millions of sources). The grid comprises all evolutionary states from the embedded Class 0 sources through Class III and debris disks. Stellar masses range from 0.1-40 solar masses and stellar temperatures from 2500-42000K. We will demonstrate proof-of-concept of the fitter using known Taurus sources, and show the limitations on trying to fit a small spectral range (e.g., the most common 1-10 micron range) with these same sources. For example, we find that several sources can be fitted with Class I (envelopes) or Class II (disks) models if only 1-10 micron data are available.  We will also show results of fitting models to sources in 2MASS/GLIMPSE data of selected star formation regions.