Unblended and slightly blended transitions of Aa-n-C₃H₇OH detected towards G+0.693. The histogram, grey shaded area, colour lines, and labels are as in Fig. 2. Red lines indicate the best LTE fit to the lines of Aa-n-C₃H₇OH reported in Table 1. The frequencies of the lines are shown in the upper part of each panel, while the red asterisks indicate the transitions that contribute to the identification of Aa-n-C₃H₇OH. Dotted black lines indicate the 3 × rms level in intensity in the spectra. Dotted red lines show the detectability limit in the integrated area defined as , with N the number of channels across the line width.