Comparison of the observed (in magenta: spectrum and photometric flux-points) and model SEDs of V339 Del. During the fireball stage (2013, Aug. 14.84 to 19.89), the model SED is represented by a synthetic spectrum (blue line, Eq. (1)), while during the following stage with a harder spectrum (bottom row of panels) the model SED (black line) is given by a superposition of the radiation from the WD pseudophotosphere (blue line) and the nebula (green line) according to Eq. (2).