  Hydrodynamic expansion of the hot fireball created in relativistic Au-Au
collisions at 200GeV in 3+1-dimensions is studied. We obtain a simultaneous,
satisfactory description of the transverse momentum spectra, elliptic flow and
pion correlation radii for different collision centralities and different
rapidities. Early initial time of the evolution is required to reproduce the
interferometry data, which provides a strong indication of the early onset of
collectivity. We can also constraint the shape of the initial energy density in
the beam direction, with a relatively high initial energy density at the center
of the fireball.
