  The magnetism in the ferromagnetic superconductor UCoGe has been studied
using a combination of magnetic Compton scattering, bulk magnetization, X-ray
magnetic circular dichroism and electronic structure calculations, in order to
determine the spin and orbital moments. The experimentally observed total spin
moment, $M_s$, was found to be -0.24 $\pm$ 0.05~$\mu_B$ at 5~T. By comparison
with the total moment of 0.16 $\pm$ 0.01~$\mu_B$, the orbital moment, $M_l$,
was determined to be 0.40 $\pm$ 0.05~$\mu_B$. The U and Co spin moments were
determined to be antiparallel. We find that the U 5\textit{f} electrons carry a
spin moment of U$_s \approx$ -0.30~$\mu_B$ and that there is a Co spin moment
of Co$_s \approx$ 0.06~$\mu_B$ induced via hybridization. The ratio
U$_l/$U$_s$, of $-1.3 \pm 0.3$, shows the U moment to be itinerant. In order to
ensure an accurate description of the properties of 5\textit{f} systems, and to
provide a critical test of the theoretical approaches, it is clearly necessary
to obtain experimental data for both the spin and orbital moments, rather than
just the total magnetic moment. This can be achieved simply by measuring the
spin moment with magnetic Compton scattering and comparing this to the total
moment from bulk magnetization.
