Preliminary results on the direct photon excess ratio for the HADES experiment

Measurements of direct photons from PHENIX and ALICE experiments at high energies show an unexpectedly high yield combined with a large elliptic flow. Both observations cannot be reconciled with current models describing the evolution of the fireball. In order to provide additional empirical data to this discussion, we analyze data on Au+Au collisions at 1.23 AGeV taken by the HADES experiment at GSI Helmholtzzentrum, Darmstadt. We present first results on the direct photon excess ratio as a function of transverse momentum and an estimate of the corresponding systematic uncertainties.