NMR spectroscopy of rotating superfluid $^3$He (Soviet-Finnish Project ROTA Research)

Experimental and theoretical studies of the properties of superfluid phases of rotating liquid $^3$He are reviewed. The observational data on nonsingular vortex textures in the rotating A phase as well as experiments revealing a structural transition inside the cores of vortices in the A phase are discussed. The gyromagnetic effect in the rotating B phase, due to the spontaneous magnetization of the vortex cores, is described.