Fast radiative cooling of anthracene cations (C14H10)+ is studied with a compact electrostatic storage device, the Mini-Ring up to 10 ms. The time evolution of the internal energy distribution of the stored ions is probed using laser-induced dissociation. The population decay due to radiative emission is measured to vary from 25 to 450 s–1 as a function of internal energy from 6 to 7.4 eV. After corrections of the infrared emission effect via vibrational transitions, the Poincaré fluorescence due to electronic transitions from thermally excited electronic states is found to be dominated in the studied energy range.