Neural Networks and the Classification of Active Galactic Nucleus   Spectra
  The use of Artificial Neural Networks (ANNs) as a classifier of digital spectra is investigated. Using both simulated and real data, it is shown that neural networks can be trained to discriminate between the spectra of different classes of active galactic nucleus (AGN) with realistic sample sizes and signal-to-noise ratios. By working in the Fourier domain, neural nets can classify objects without knowledge of their redshifts. 
Daya M. Rawson, Jeremy Bailey and Paul J. Francis