Symmetry constraints for the emission angle dependence of Hanbury   Brown--Twiss radii
  We discuss symmetry constraints on the azimuthal oscillations of two-particle correlation (Hanbury Brown--Twiss interferometry) radii for non-central collisions between equal spherical nuclei. We also propose a new method for correcting in a model-independent way the emission angle dependent correlation function for finite event plane resolution and angular binning effects. 
U.W. Heinz, A. Hummel, M.A. Lisa, and U.A. Wiedemann