Measurements of N2O5 in the stratosphere and of its spectrum at 1240 cm-1 in the laboratory are reviewed. Errors in previous publications about N2O5 are discussed briefly. The earliest stratospheric measurement is significantly revised in the light of new measurements of band strength. All the measured profiles are tabulated using a standard value for the band strength; they can be linearly scaled if future, more accurate, measurements suggest that a different value should be used. ¿ American Geophysical Union 1991