The CMB-Galactic contributions

This paper reviews the Galactic foregrounds which are to be taken into acco unt when an accurate estimate is required of the CMB fluctuation power spec trum. These include synchrotron, free-free and duet emission, all of which contribute at Planet LFI frequencies. Foreground polarization contamination of intrinsic CMB polarization is about a factor of 5 greater than the case of total intensity. There are indications at microwave frequencies of a co mponent arising from small spinning grains. Areas of low foreground emissio n cover 20-30 percent of the sky: these will give the best estimates of the intrinsic CMB power spectrum.