The knowledge of the magnitude and coherence length of the random
component of the Galactic Magnetic Field (GMF) is of fundamental
importance for establishing the rigidity threshold above which
astronomy with charged particles is possible.
Here we present a new study of the random component of the GMF using
synchrotron intensity as measured by Planck, WMAP and Haslam et al and
combine it for the first time with the observed fluctuations of the
rotation measures of extragalactic radio sources. This combined
information allows us to constrain both, the strength and coherence
length of random magnetic field in the Galaxy.