“…Due to this practical importance there are a lot of papers by engineers and physicists on the inversion of the Funk transform, see e.g. [1,4,6,10,13,22,23,28,29,31,32,34,35,37,38,43]. There are also a few mathematical papers on this topic covering quite different inversion methods, i.e., splines [3,12,40], Fourier expansion [11], Gabor frames [7] and wavelets [2].…”