Observed spectra after baseline removal for the second observation window (February 2012) at 66.44 μm (top) and 67.09 μm (bottom). The spectra are presented as line-to-continuum ratio minus one. The scatter in the peak position of the line is mainly due to Doppler shift induced by Saturn’s rapid rotation. For both observations, all the plotted spectra correspond to the pointings selected within the planetary disc, as shown with the black dots on Fig. 2 second row (i.e. second observation window).