Detection of the extra-Galactic background fluctuations at 170 mu m

We have used the Maranol field observations with ISOPHOT at 170 mu m to sea rch for the Cosmic Far-InfraRed Background fluctuations. This field is part of the FIRBACK project (Puget et al. 1999). For the first time, fluctuatio ns due to unresolved extra-Galactic sources are isolated. The emission of s uch sources clearly dominates, at arcminute scales, the background fluctuat ions in the lowest Galactic emission regions. The study presented here is b ased on a power spectrum analysis which allow to statistically separate eac h of the background components. With this analysis, we clearly show that we detect the CFIRB fluctuations.