Spectral Classification of Galaxies using the Principal Component
  Analysis: a Web Based Tool
  We have developed a web tool to perform Principal Component Analysis (PCA,
Murtagh & Heck 1987; Kendall 1980) onto spectral data. The method is especially
designed to perform spectral classification of galaxies from a sample of input
spectra, giving the set of orthonormal vectors called Principal Components
(PCs) and the corresponding projections. The first two projections of the
galaxy spectra onto the PCs are known to correlate with the morphological type
(Connolly et al. 1995) and, following Galaz & de Lapparent (1998), we use the
parameters \delta and \theta which define a spectral classification sequence of
typical galaxies from ellipticals to late spirals and star-forming galaxies.
The program runs in the website http://azul.astro.puc.cl/PCA/ and can be used
without downloading any binary files or building archives of any kind.
