Top: SED plot for the A68/nn4 stellar population with non-detections shown by 1σ upper limits. For such a strongly obscured galaxy, the two extinction laws produce quite different slopes, with the Calzetti law being unable to reproduce the steep photometry at the 1σ level. Allowing for more extinction (A_V ≥ 4) could not offer a better fit since this law is relatively flat, and it would have worsen the minimization in the rest-frame optical domain. The SMCibased solution, on the other hand, is steep enough. The nebular lines are relatively weak, since despite the very young age they are also absorbed, and have little effect on the solution here. Bottom: full SED fit (red), obtained with the template of IRAS 20551-4250 from the P07 library, with an additional SMC-based extinction of A_V = 0.4. Given the intrinsic attenuation of the template and its characteristic 2175 Å bump, adding more extinction in order to pass beneath the 1σ-detection limits was not possible. The best fit of the FIR data (green) was obtained with the CE01 library.