SIRTF Tools for DIRT

The Dust InfraRed ToolBox (DIRT-a part of the Web Infrared ToolShed, or WITS1) is a Java applet for modeling astrophysical processes in circumstellar shells around young and evolved stars.(2) DIRT has been used by the astrophysics community for about 5 years. Users can automatically and efficiently search grids of pre-calculated models to fit their data. A large set of physical parameters and dust types are included in the model database, which contains over 500,000 models. We are adding new functionality to DIRT to support new missions like SIRTF and SOFIA. A new Instrument module allows for plotting of the model points convolved with the spatial and spectral responses of the selected instrument. This lets users better fit data from specific instruments. Currently, we have implemented modules for the Infrared Array Camera (IRAC) and Multiband Imaging Photometer (MIPS) on SIRTF. The models are based on the dust radiation transfer code of Wolfire & Cassinelli (1986) which accounts for multiple grain sizes and compositions. The model outputs are averaged over the instrument bands using the same weighting (v F-v = constant) as the SIRTF data pipeline which allows the SIRTF data products to be compared directly with the model database.