Propane on Titan

We present the first observations of propane (C${}_3$H${}_8$) on Titan that unambiguously resolve propane features from other numerous stratospheric emissions. This is accomplished using a $R=\lambda \mathrm{/}\delta \lambda \approx {10}^5$ spectrometer (TEXES) to observe propane’s ${\nu }_{26}$ rotation-vibration band near 748 cm${}^{-1}$. We find a best-fit fractional abundance of propane in Titan’s stratosphere of $(6.2\pm 1.2)\times {10}^{-7}$ in the altitude range to which we are sensitive (90-250 km or 13-0.24 mbar).