Infrared SEDs of the sample of ultraluminous infrared galaxies. Red plus symbols and solid line represent model SED. Red dashed line is the modified Planck fit for temperature determination. Black crosses represent VizieR photometry. The errors bars are shown if present in the VizieR tables, but often barely visible. The SED of Arp 220 was multiplied by 0.2, 0.3, and 0.2 for Arp 220D, Arp 220W, and Arp 220E, respectively (see Sect. 6.2).