The Cosmic Microwave Background Spectrum:an Analysis of Observations
  This work presents a detailed analysis of Cosmic Microwave Background (CMB) radiation intensity observations. The CMB is a relic of the Big Bang and its study greatly enhances our knowledge of cosmology. This work has led to new values for the best fit temperature $2.7356 \pm 0.0038$ K (95% CL) and the speed of our solar system relative to the CMB, and limits on the spectral distortion parameters: $\mu$, $y$, and $Y_{ff}$. These in turn lead to tighter constraints on the thermal history and allowed energy release in the early universe and possible cosmological processes. These limits are approaching the order of magnitude required by known processes. 
Henrik P. Nordberg, George F. Smoot