Due to its electromagnetic nature, thermal radiation produced in the most central heavy ion collisions is expected to be one of the cleanest probes for the temperature of the deconfined state of matter that is formed. At RHIC, direct photons from deuteron-gold collisions can be used, both to disentangle initial and final state effects that appear in gold-gold reactions and to study nuclear effects, such as the existence of a Color Glass Condensate. Results obtained in d+Au with the STAR barrel calorimeter are presented and the prospects for Au+Au will be discussed.