PROCEEDINGS ARTICLE | July 28, 2008
Proc. SPIE. 7013, Optical and Infrared Interferometry
KEYWORDS: Human-machine interfaces, Stars, Data modeling, Fourier transforms, Interferometry, Java, Optical interferometry, Photometry, Surface conduction electron emitter displays, Visibility
LITpro is a software for fitting models on data obtained from various stellar optical interferometers, like the VLTI. As a
baseline, for modeling the object, it provides a set of elementary geometrical and center-to-limb darkening functions, all
combinable together. But it is also designed to make very easy the implementation of more specific models with their
own parameters, to be able to use models closer to astrophysical considerations. So LITpro only requires the modeling
functions to compute the Fourier transform of the object at given spatial frequencies, and wavelengths and time if needed.
From this, LITpro computes all the necessary quantities as needed (e.g. visibilities, spectral energy distribution, partial
derivatives of the model, map of the object model). The fitting engine, especially designed for this kind of optimization, is
based on a modified Levenberg-Marquardt algorithm and has been successfully tested on real data in a prototype version.
It includes a Trust Region Method, minimizing a heterogeneous non-linear and non-convex criterion and allows the user
to set boundaries on free parameters. From a robust local minimization algorithm and a starting points strategy, a global
optimization solution is effectively achieved. Tools have been developped to help users to find the global minimum. LITpro
is also designed for performing fitting on heterogeneous data. It will be shown, on an example, how it fits simultaneously
interferometric data and spectral energy distribution, with some benefits on the reliability of the solution and a better
estimation of errors and correlations on the parameters. That is indeed necessary since present interferometric data are
generally multi-wavelengths.
