Raytracing Software for the Simulation of the Solar K-Corona

In this talk we will present RAYTRACE, a raytracing software developed at the U.S. Naval Research Laboratory. The program is an implementation of the Thomson scattering equations applied to the solar corona (Billings 1966). Synthetic coronal images in total or polarized brightness can be calculated using models of various coronal structures. We have implemented many models for quiescent and dynamic coronal stuctures such as streamers, the heliospheric current sheet (HCS), jets and CMEs. The models are generally analytic representations of the volume electron density, but a generic data cube of electron density can also be used. The core of the program has been written in C++ pimarily for computation speed. An earlier version was written in IDL, but was quite slow. Due to the processing speed of common computers, a high resolution image (512 x 512) of the HCS streamer belt for instance can be generated in less than 1 minute (Pentium 4, 2.5 GHz, 512 Mb RAM, Linux OS). A graphical user interface has been developed in IDL and allows the user to easily enter the parameters required for each model, specifying the position and orientation of the observer and structure, the size and resolution of the images, and then to visualize the output and compare the results to actual coronal images obtained by SOHO/LASCO and in the future by the STEREO/SECCHI coronagraphs (COR1 and COR2). Some of the main features of the front-end interface include mesh plot positioning of structures in space, parameter tuning for the structures and movie making. Different studies have already been done using this software, such as the inversion of the electron density of the streamer belt or the modeling of CMEs for the STEREO mission (presented in another paper at this meeting).