  We study single- and double-inclusive spectra of thermal photons, produced in
heavy-ion collisions at $\sqrt{s}=200$ AGeV within a realistic space-time
framework which combines the Parton-Cascade-Model and 3-dimensional
hydrodynamics (HYLANDER). This allows also for the first time to take into
account pre-equilibrium effects for photon production. A rapid decrease in the
width of the correlation function as the photon transverse momentum drops below
$\sim 1.5$ GeV is a signature of the deconfinement phase transition.
