Applications of the Filter Diagonalization Special Estimator in Helioseismology W. Dappen, A. Jones, D. Belkic, and H. Taylor, Univ. of Southern California The Filter Diagonalization (FD) method of spectral estimation has been developed at USC as a general tool for spectral analysis (Mandelshtam & Taylor 1997). this is a proposal to extend the technique and investigate its applicability to helioseismology and the analysis of data from the MDI, VIRGO and GOLF instruments on SoHO. Unlike traditional Fourier techniques, the frequency resolution of FD is not limited by the sample spacing. In essence the method is an optimized means to fit damped sinusoids to the data. In the case of solar oscillations this is a very good model. Using FD to analyze short time series could provide a means to study mode dynamics and so learn more about the excitation mechanisms. Along with the enhanced spectral resolution, FD provides flexibility in the choice of basis functions for the spectral decomposition. Exploiting this flexibility the possibility to reduce spectral noise is demonstrated. Such techniques would prove useful in, for example, analyzing the noisy spectra generated by the ring analysis approach to local helioseismology. At present the FD code is stable and portable, but not user friendly. It is proposed to provide a portable graphical interface to the code, and to investigate interfaces to standard analysis packages such as IRAF and IDL. The code and interfaces will be provided to the community via the internet.