Sulphur trioxide (SO3) is a trace species in the atmospheres of the Earth
and Venus, as well as well as being an industrial product and an environmental
pollutant. A variational line list for 32S16O3, named UYT2, is
presented containing 21 billion vibration-rotation transitions. UYT2 can be
used to model infrared spectra of SO3 at wavelengths longwards of 2 μm
(ν<5000 cm−1) for temperatures up to 800 K. Infrared absorption
cross sections are also recorded at 300 and 500 C are used to validate the UYT2
line list. The intensities in UYT2 are scaled to match the measured cross
sections. The line list is made available in electronic form as supplementary
data to this article and at \url{www.exomol.com}.Comment: 15 pages, 10 figures, 9 tables MNRAS submitte