Hydrogen Two-Photon Continuum Emission from the Horseshoe Filament in   NGC 1275
  Far ultraviolet emission has been detected from a knot of Halpha emission in the Horseshoe filament, far out in the NGC 1275 nebula. The flux detected relative to the brightness of the Halpha line in the same spatial region is very close to that expected from Hydrogen two-photon continuum emission in the particle heating model of Ferland et al. (2009) if reddening internal to the filaments is taken into account. We find no need to invoke other sources of far ultraviolet emission such as hot stars or emission lines from CIV in intermediate temperature gas to explain these data. 
R. M. Johnstone, R. E. A. Canning, A. C. Fabian, G. J. Ferland, M.   Lykins, R. L. Porter, P. A. M. van Hoof and R. J. R. Wi...
astro-ph.CO