Inverse Problem for Static Electromagnetic Field in a Dipole   Approximation
  The following inverse problem is discussed. A static electromagnetic field generated by a limited system of charges and currents is supposed to be known with its first derivatives at a point somewhere far from the system. This allows to reconstruct the position of the system, its net charge, and the electric and magnetic moments of the system. 
V.Ya. Epp, G.F. Kopytov and T.G. Mitrofanova