Overview of a-type (–) HOCH₂CN transitions covered by the PILS spectrum towards the half-beam offset position of IRAS 16293B, illustrating the detection of a number of these lines. The observed spectrum is plotted in black and synthetic spectra for a column density of 3.0 × 10¹⁵ cm⁻² and excitation temperatures of 150 (blue) and 300 K (red) are overplotted. The quantum numbers of the transition are indicated at the top of each panel and the upper state energy is given in the top left of each panel.