We aim to summarize the current state of knowledge regarding Galactic Faraday rotation in an all-sky map of the Galactic Faraday depth .
For this we have assembled the most extensive catalog of Faraday rotation data of compact extragalactic polarized radio sources to date .
In the map making procedure we use a recently developed algorithm that reconstructs the map and the power spectrum of a statistically isotropic and homogeneous field while taking into account uncertainties in the noise statistics .
This procedure is able to identify some rotation angles that are offset by an integer multiple of \pi .
The resulting map can be seen as an improved version of earlier such maps and is made publicly available , along with a map of its uncertainty .
For the angular power spectrum we find a power law behavior C _ { \ell } \propto \ell ^ { -2.17 } for a Faraday sky where an overall variance profile as a function of Galactic latitude has been removed , in agreement with earlier work .
We show that this is in accordance with a 3D Fourier power spectrum P ( k ) \propto k ^ { -2.17 } of the underlying field n _ { \mathrm { e } } B _ { r } under simplifying geometrical and statistical assumptions .