Full ULIRG SEDs and defining photometric points. Between 5 and 36 μm the SEDs are based on IRS spectra rather than the photometry. The curves have been offset for clarity; from top to bottom the galaxies and offset factors are: (1) IRAS 22491-1808 (1); (2) IRAS 14348-1447 (0.1); (3) IRAS 17208-0018 (0.003); (4) Arp 220 (0.00007); (5) IRAS 12112+0305 (0.00005); (6) Dale alpha = 1.5 model; and (7) Chary & Elbaz L(TIR) = 2 × 10 ¹² model.