The effect of a spatially varying Galactic spectral index on the maximum   entropy reconstruction of Planck Surveyor satellite data
  We study the effect of Galactic foregrounds with spatially varying spectral indices on analysis of simulated data from the Planck Satellite. We also briefly mention the effect the extra-galactic point sources have on the data analysis and summarise the most recent constraints on Galactic emission at GHz frequencies. 
A.W. Jones, M.P. Hobson, P. Mukherjee and A.N. Lasenby