The absorption spectrum of ozone was recorded at low temperatures (down to −135 °C) by high resolution Fourier transform spectrometry and intra cavity laser absorption spectroscopy (ICLAS) near 10,400 cm^−1. A preliminary analysis of the rotational structure of the absorption spectra of ¹⁶O₃ and ¹⁸O₃ shows that this spectral region corresponds to a superposition of two different electronic transitions, one with a very broad rotational structure, showing for the first time the asymmetric stretching frequency mode ν₃ of the electronic state ³A₂, the other formed by a completely diffuse band, probably the 2₀¹ band of a new transition due to the triplet electronic state ³B₂. Predissociation effects induce large broadening of the rotational lines for the transition centered at 10,473 cm^−1 identified as the 3₀² band of the ³A₂ â†� X¹A₁ electronic transition. The rotational structure cannot be analyzed directly but instead the band contour method was used to confirm the symmetry of the transition and to estimate the spectroscopic constants for the ¹⁶O isotopomer. The origin of the band is at 10,473±3 cm^−1 and the value of the ¹⁶O₃(³A₂) antisymmetric stretching frequency mode is equal to 460±2 cm^−1. We believe that the diffuse band is due to the ³B₂ state and is located at about 10,363±3 cm^−1 for ¹⁶O₃ and 10,354±3 cm^−1 for ¹⁸O₃. The isotopic rules confirm the different results obtained for ¹⁸O₃ and ¹⁶O₃.